WO2021152479A1 - Nanostructured article - Google Patents

Abstract

A nanostructured article (800) includes a substrate, a plurality of first nanostructures (803) disposed on, and extending away from, the substrate (805); and a covalently crosslinked fluorinated polymeric 1ayer (801) disposed on the plurality of first nanostructures (803). The plurality of first nanostructures (803) includes at least one polymer which includes a first polymer including (meth)acrylic acid monomer units. The polymeric layer at least partially fills spaces between the first nanostructures (803) to an average minimum height above the substrate of at least 30nm such that the polymeric layer has a nanostructured surface (807) defined by, and facing away from, the plurality of first nanostructures (803).

Description

NANOSTRUCTURED ARTICLE

Background

Articles having nanostructured surfaces are known. In some cases, a nanostructured surface may be hydrophobic.

Summary

The present disclosure relates generally to nanostructured articles. The nanostructured articles can have a hydrophobic (often superhydrophobic) or omniphobic (often superomniphobic) surface that has improved mechanical performance and/or optical performance compared to traditional nanostructured surfaces. The nanostructured article typically includes at least one layer including at least one polymer that includes a first polymer which includes (meth)acrylic acid monomer units. The at least one polymer can include a second polymer blended with the first polymer. Surface modified metal oxide nanoparticles may be dispersed in the at least one polymer.

In some aspects of the present description, a nanostructured article including a substrate; a plurality of first nanostructures disposed on, and extending away from, the substrate; and a covalently crosslinked fluorinated polymeric layer disposed on the plurality of first nanostructures is provided. The plurality of first nanostructures includes at least one polymer, where the at least one polymer includes a first polymer including (meth)acrylic acid monomer units. The covalently crosslinked fluorinated polymeric layer at least partially fills spaces between the first nanostructures to an average minimum height above the substrate of at least 30 nm such that the polymeric layer has a nanostructured surface defined by, and facing away from, the plurality of first nanostructures.

In some aspects of the present description, a nanostructured article including a substrate and a plurality of first nanostructures disposed on the substrate is provided. The plurality of first nanostructures includes at least one polymer, where the at least one polymer includes a first polymer including (meth)acrylic acid monomer units. The plurality of first nanostructures extends away from the substrate along a length of the first nanostructures. The plurality of first nanostructures has an average length L1 and an average width W1. W1 is preferably in a range of 5 nm to 500 nm. L1/W1 is preferably at least 1.

In some aspects of the present description, a nanostructured article including a first layer and a plurality of first nanostructures integrally formed with first layer is provided. The first layer includes at least one polymer, where the at least one polymer includes a first polymer including (meth)acrylic acid monomer units. The plurality of first nanostructures extend away from the first layer along a length of the first nanostructures. The plurality of first nanostructures have an average length L1 and an average width W1. W1 is preferably in a range of 5 nm to 500 nm. L1/W1 is preferably at least 1. These and other aspects will be apparent from the following detailed description. In no event, however, should this brief summary be construed to limit the claimable subject matter.

Brief Description of the Drawings

FIGS. 1-6 are schematic cross-sectional views of nanostructured articles;

FIG. 7 is a schematic cross-sectional view of a nanostructured article including a conformal layer;

FIGS. 8-12 are schematic cross-sectional views of nanostructured articles that include a layer disposed on a plurality of nanostructures;

FIGS. 13-15 are schematic cross-sectional views of substrates;

FIG. 16 is a schematic cross-sectional view of a nanostructured article including a multilayer film substrate;

FIGS. 17A-17B schematically illustrate applying a first nanostructured article to a surface to form a second nanostructured article;

FIGS. 18A-18C schematically illustrate integrally forming a nanostructured article with a structural member;

FIG. 19 is a schematic cross-sectional view of a system including a nanostructured article and an electronic device;

FIG. 20 is a schematic front perspective view of an automobile; and

FIG. 21 is a schematic rear view of an automobile.

Detailed Description

In the following description, reference is made to the accompanying drawings that form a part hereof and in which various embodiments are shown by way of illustration. The drawings are not necessarily to scale. It is to be understood that other embodiments are contemplated and may be made without departing from the scope or spirit of the present description. The following detailed description, therefore, is not to be taken in a limiting sense.

Nanostructured articles described herein have been found to provide a hydrophobic or superhydrophobic, or omniphobic or superomniphobic, surface that has improved mechanical performance (e.g., abrasion resistance and/or durability) and/or optical performance (e.g., low haze and/or high optical transmittance for visible light or for other wavelength or frequency ranges appropriate for a given application such as an infrared range or a GHz frequency range) compared to traditional nanostructured surfaces. In some embodiments, the nanostructured articles are protective cover films that protect a surface of interest from water or ice build-up, for example, that could otherwise affect performance of a device proximate to the surface of interest. In some embodiments, the nanostructured article is a flexible film that includes an adhesive layer for attaching the film to the surface. In some embodiments, the nanostructured article may be integrally formed with an exterior layer of a structural member (e.g., an injection molded part). In some embodiments, a nanostructured article utilizes ionomeric or nanocomposite materials described further elsewhere herein. For example, an ionomeric or nanocomposite material can include at least one polymer where the at least one polymer includes a first polymer including (meth)acrylic acid monomer units. The first polymer can be an ethylene acrylic acid copolymer or an ethylene methacrylic acid copolymer, for example. In some embodiments, a plurality of nanoparticles is dispersed in the at least one polymer to provide a nanocomposite. The nanoparticles can be or include metal oxide nanoparticles which can be surface modified with a carboxylic acid silane surface modifying agent.

Conventional ionic elastomers possess some of desired properties such as high visible transmission and low haze, chemical resistance, and flexibility. However, conventional ionic elastomeric polymers are limited in mechanical properties or abrasion resistance, impact resistance, tensile modulus, for example.

Particulate fillers have been incorporated into polymers to improve mechanical properties. However, the vast majority of commercially available filled polymers are opaque and thus are unsuitable for use in optical articles. Additionally, rigid particulate fillers can adversely affect the flexibility properties of the polymers with which they are combined.

One technique for providing modified properties is to blend polymeric materials. This approach can be problematic as the preparation of blends to improve one property, such as flexibility, can adversely affect other properties, such as optical properties. This is especially true for optical properties, since the vast majority of polymer blends have at least some degree of immiscibility. A lack of miscibility can dramatically affect optical properties such as visible light transmission, haze and clarity. Even polymers that have the same or similar monomeric composition can be immiscible, if, for example, the polymers have differing degrees of branching. Thus, modification of a polymeric composition by blending the polymeric composition with another polymer, even a seemingly similar polymer, is not a trivial undertaking, especially when the blended composition has desired optical properties. It has been unexpectedly found that blends of different polymers including similar content of (meth)acrylic acid monomer units provide improved mechanical properties while maintaining desired optical properties (e.g., high optical transparency and/or low optical haze).

The ionomers and nanocomposites of the present disclosure achieve the contradictory goals of flexibility, optical transparency and improved mechanical properties, according to some embodiments.

The terms “miscible” or “miscibility” refer to at least two polymers that are compatible with each other such that blends of the at least two polymers do not phase separate so as to form phase separated microdomains that are large enough to produce significant scattering of visible light (wavelengths of about 400 to about 700 nm).

The terms “immiscible” or “immiscibility” refer to at least two polymers that are incompatible with each other such that blends of the at least two polymers phase separate so as to form phase separated microdomains that are large enough to produce significant scattering of visible light (wavelengths of about 400 to about 700 nm) resulting in unacceptable haze. The nanocomposites of the present disclosure utilize metal oxide nanoparticles, which are particles with an average diameter that is in the nanometer range. These particles give improved mechanical properties to the nanocomposites, and because of their small size, according to some embodiments, the nanoparticles do not appreciably scatter visible light. The nanoparticles can be surface modified to achieve compatibility with the at least one polymer to avoid agglomeration or aggregation of the nanoparticles in the nanocomposite which would lead to inferior optical properties. The surface modifying agent is typically a carboxylic acid-functional silane. While not wishing to be bound by theory, it is believed that the acid-functional groups on the surface modifying agent improve the compatibility of the particles with the acid-functional (meth)acrylic polymer(s) of the at least one polymer. Some of the acid-functional groups on the surface-modified nanoparticles may also be neutralized like at least some of the acid-functional groups on the (meth)acrylic polymer(s). Acid-functional groups in the surface modifying agent are preferred for dispersibility of the nanoparticles in water. The acid groups of the acid silane, when added to the basic surface unmodified nanoparticle solution (for example, NACLO 2327), are at least partially neutralized which renders the silane soluble in the aqueous phase such that the surface of the silica can be modified readily. Furthermore, it has been found that in the coating and melt processing of the ionic elastomer nanocomposite materials that the acid silane on the surface of the particles can allow for interaction of the nanoparticles with the ionic groups of the elastic ionomer polymers leading to excellent compatibility of the nanoparticles in the host polymer matrix.

In some embodiments, a nanostructured article includes a nanostructured polymeric or ionomeric or nanocomposite layer which exhibits the ability to be deformed by an external implement (for example by a Delrin stylus or pencil) and recover its original shape with either time or the application of heat. It has been found that polyurethane layers, such as covalently crosslinked (crosslinked via covalent bonds) polyurethane layers, are useful for this layer. Such layers have been found to provide useful hydrophobicity even without the addition of a fluorinated coating when the layer is nanostructured. Other useful materials for this nanostructured layer include the ionomeric or nanocomposite layers describe herein. Alternatively, an ionomeric or nanocomposite layer described herein can be disposed behind a polyurethane layer which is nanostructured. Further, according to some embodiments, such nanostructured layers have been found to have a high optical transmittance (e.g., an average optical transmittance of at least 80%, or at least 85%, or at least 90%, or at least 92% in a predetermined wavelength or frequency range such as 400 nm to 700 nm, or an infrared range or a GHz frequency range), a low haze (e.g., a haze of less than 5%, or less than 3%, or less than 2%, or less than 1%), and a high durability. In addition, it has been found that overcoating the nanostructures with a covalently crosslinked fluorinated polymeric layer substantially improves the durability and omniphobicity of the nanostructured surface. For example, it has been found that the nanostructures of a covalently crosslinked shape memory polyurethane layer, or of an ionomeric or nanocomposite layer described herein, may not recover their shape when pushed down into contact with one another (e.g., due to an impact) since the nanostructures can stick together and this can prevent their recovery. However, it has been found that when coated with a covalently crosslinked fluorinated polymeric layer that the nanostructures are prevented from sticking together and can recover their initial shape even after an impact presses the nanostructures together.

Nanostructured articles described herein may be made by imparting a suitable nanostructure to a substrate (e.g., a nanocomposite or ionomeric layer described herein or a multilayer film including a polyurethane layer disposed one a nanocomposite or ionomeric layer). This structure can be imparted via any suitable method. One suitable method for imparting this structure includes casting urethane or coating molten ionomeric or nanocomposite material onto a nanostructured tool such that the urethane or ionomeric or nanocomposite material conforms to the nanostructured surface of the tool and solidifies (e.g., cures or dries) into a solid polyurethane or ionomeric or nanocomposite layer having a complementary structure. Such structured tools can be made via known tooling methods using processes such as diamond turning, photolithographic processes, deposition of an etch resist material and followed by plasma etching, or direct write reactive ion etching processes, for example. Other suitable methods of imparting a random nanostructure onto the surface of a layer are based on plasma processing techniques as described in U.S. Pat. Nos. 5,888,594 (David et al.), 10,119,190 (David et al.) and 10,134,566 (David et al.), for example, and in U.S. Pat. Appl. Pub. Nos. 2012/0012557 (David et al.), 2016/0370605 (David et al.), 2013/0038949 (David et al.), and 2017/0067150 (David et al.), for example. In some embodiments, the nanostructure can be imparted by the combination of creating randomly placed silica islands on the surface of the layer which act as etch resists in a subsequent plasma etching process to create posts on a surface of the layer.

As used herein, the term “nanostructure” or “nanostructured” refers to an article or surface having at least one nanoscale feature or structure having dimensions on the order of about 5 nm to about 500 nm. The nanostructured surface can have a nanostructured anisotropic surface. The nanostructured anisotropic surface can include nanoscale features having a height to width ratio of at least 1, or at least 2, or at least 3, or at least 5, or at least 10, or at least 20. For example, the height to width ratio may be in a range of 1 to 100, or 1 to 50, or 3 to 20. The nanostructured anisotropic surface can include nanofeatures such as, for example, nano-pillars or nano-columns. In some embodiments, the nanostructures have steep side walls that may be perpendicular to the substrate or may extend at a predetermined oblique angle to the substrate. In some embodiments, at least a majority of the nanostructures are capped with mask material (e.g., an inorganic silica nanoparticle or an inorganic silica island).

In some embodiments, a nanostructured article includes a nanostructured polyurethane or ionomeric or nanocomposite layer having a nanostructured surface. In some embodiments, the nanostructured surface is hydrophobic. Surfaces may be hydrophobic due to the chemical nature of the film. Alternatively, or additionally, surfaces can be made hydrophobic using treatments on the surface, coatings on the surface or, potentially, by incorporating (e.g., melt) additives. For example, the films can be processed as described in U.S. Patent Nos. 8,974,590 (Russell et al.); 8,741,158 (Aytug et al.); 7,396,866 (Jariwala et al.); and 9,085,019 (Zhang et al.). The nanostructured surface may be one or more of hydrophobic (e.g., advancing water contact angle of at least 100 degrees and a water contact angle hysteresis of less than 40 degrees), superhydrophobic (e.g., advancing water contact angle of at least 130 degrees, or at least 140 degrees, or at least 150 degrees and a water contact angle hysteresis of less than 20 degrees), omniphobic (e.g., hydrophobic and having an advancing hexadecane contact angle of at least 70 degrees), or superomniphobic (e.g., superhydrophobic and having an advancing hexadecane contact angle of at least 80 degrees or at least 90 degrees). The degree of hydrophobicity or omniphobicity can be increased by increasing the fluorine content, for example, in the nanostructured surface. In some embodiments, a suitable degree of hydrophobicity or omniphobicity is obtained by nanostructuring a polyurethane or an ionomeric or nanocomposite material as described herein. In some embodiments, additional treatments and/or coatings may be applied to the nanostructured surface to make the surface additionally hydrophobic and/or additionally omniphobic. In some embodiments, the nanostructured surface is coated with a conformal glass like layer or a diamond like glass (DLG) layer as described further elsewhere herein. In some such embodiments, a low surface energy layer (e.g., a covalently crosslinked fluorinated polymeric layer) is coated over the DLG layer. In other embodiments, the low surface energy layer may be coated over the nanostructures without using a DLG layer or with using a different layer that can function as a tie layer for improving the bonding of the low surface energy layer to the nanostructured substrate.

Advancing, receding, and static contact angles can be measured with a goniometer. Contact angle measurements are described in 9,085,019 (Zhang et al.), for example. The contact angle hysteresis is the difference between the advancing and receding contact angles. In some embodiments, the nanostructured surface has an advancing water contact angle of at least 100 degrees, or at least 120 degrees. In some preferred embodiments, the advancing water contact angle is at least 130 degrees, or at least 140 degrees, or at least 150 degrees, or at least 155 degrees, or even at least 160 degrees. In some embodiments, the static water contact angle is also in one of these ranges. For example, in some embodiments, the nanostructured surface has a static water contact angle of at least 100 degrees, or at least 120 degrees, or at least 130 degrees, or at least 140 degrees, or at least 150 degrees, or at least 155 degrees, or at least 160 degrees. In some embodiments, the water contact angle hysteresis is less than 40 degrees, or less than 30 degrees, or less than 20 degrees, or less than 15 degrees, or less than 10 degrees, or less than 5 degrees. In some embodiments, the nanostructured surface has an advancing hexadecane contact angle of at least 70 degrees, or at least 80 degrees or at least 90 degrees, or at least 100 degrees. In some embodiments, the nanostructured surface has a water roll-off angle of no more than 30 degrees, no more than 20 degrees, or no more than 15 degrees, or no more than 10 degrees, or no more than 8 degrees.

Traditional nanostructured polymeric films that are capable of providing a high degree of omniphobicity have sacrificed optical properties such as transparency and/or haze. According to some embodiments of the present description, a nanostructured article can include a plurality of polymeric nanostructures defining a nanostructured surface having an advancing water contact angle of at least 130 degrees and an advancing hexadecane contact angle of at least 80 degrees, and at the same time the nanostructured article can have an average optical transmittance of at least 90% and an optical haze of less than 5%. In some such embodiments, the optical haze is less than 3%, or less than 2%, or less than 1%. In some such embodiments or in other embodiments, the nanostructured article has an optical clarity of at least 90%, or at least 95%, or at least 98%, or at least 99%. In some embodiments, the nanostructured surface has an advancing water contact angle of at least 140 degrees or at least 150 degrees, and an advancing hexadecane contact angle of at least 90 degrees The average optical transmittance can be determined by averaging (unweighted mean) the transmittance in the visible range (wavelengths in the range from 400 nm to 700 nm), or in another range when specified, for normally incident light. The average optical transmittance can alternatively be determined as the luminous transmittance as described in the ASTM D1003-13 test standard. The optical haze can be determined as described in the ASTM D 1003- 13 test standard. The optical clarity can be determined according to the ASTM D1746-15 test standard. The average optical transmittance, optical haze and optical clarity may be determined with the nanostructured surface facing toward or away from the light source. In some embodiments, the optical clarity is determined with the nanostructured surface facing away from the light source, and the average optical transmittance and optical haze are determined with the nanostructured surface facing the light source. Luminous transmission, clarity, and haze can be measured using a BYK- Gardner Haze-Gard Plus model 4725 or a BYK-Gardner Haze-Gard i (available from BYK-Gardner Columbia, MD), for example. In some embodiments, the nanostructured article has a transmittance for normally incident light at one or more predetermined wavelengths of at least 90% where the one or more predetermined wavelengths includes at least one non-visible wavelength (e.g., an infrared wavelength). For example, the nanostructured article may be used to protect a sensor system (e.g., LIDAR) that operates at a wavelength of about 830 nm or about 905 nm, for example, and the nanostructured article may have a transmittance of at least 90% for this operating wavelength. As another example, the nanostructured article may be used to protect a 5G antenna that operates in a GHz frequency range (e.g., 0.6 to 60 GHz).

FIG. 1 is a schematic cross-sectional view of a nanostructured article 100 including a substrate 105 and a plurality of first nanostructures 103 disposed on, and extending away from, the substrate 105.

In the illustrated embodiment, the substrate 105 extends generally in the x-y plane and the first nanostructures extend generally along the z-direction (out of plane direction). The plurality of first nanostructures 103 extend to an average height H1 from the substrate 105 and have an average width W1 and an average spacing S1 (e.g., mean of center-to-center distance or edge-to-edge distance). Averages refers to unweighted means unless indicated differently. The plurality of first nanostructures 103 extend away from the substrate along a length of the first nanostructures 103 and have an average length L1. In the illustrated embodiment, L1 and H1 are substantially equal.

The substrate 105 has a major surface 109 (planar top surface portion of the substrate 105) and the first nanostructures 103 extend from the major surface 109 along a direction substantially normal to the major surface 109. The nanostructured article 100 has a nanostructured surface 104 which includes the major surface 109 and the outer surface of the first nanostructures 103.

FIG. 2 is a schematic cross-sectional view of a nanostructured article 200 including a substrate 205 and a plurality of first nanostructures 203 disposed on, and extending away from, the substrate 205.

In the illustrated embodiment, the substrate 205 extends generally in the x-y plane and the first nanostructures extend in a direction tilted from the z-direction. The plurality of first nanostructures 203 extend to an average height H1 from the substrate 205 and have an average width W1 and an average spacing S1. The plurality of first nanostructures 203 extend away from the substrate along a length of the first nanostructures 203 and have an average length L1. In the illustrated embodiment, L1 is larger than H1 due to the tilt of the first nanostructures 203 from the z-axis.

The substrate 205 has a major surface 209 and the first nanostructures 203 extend from the major surface 209 along a direction making an oblique angle with the major surface 209. The nanostructured article 200 has a nanostructured surface 204 which includes the major surface 209 and the outer surface of the first nanostructures 203.

The nanostructured surface 104 or 204 may be one or more of hydrophobic, superhydrophobic, omniphobic, or superomniphobic.

The width of a nanostructure is the smallest lateral dimension of the nanostructure (smallest diameter in a cross-section orthogonal the length of the nanostructure where the diameter is a line from opposing edges of the cross-section that passes through a center of the cross-section). For example, the first nanostructures 103 or 203 may be circular cylinders where the width is the diameter, or the first nanostructures 103 or 203 may be elliptical cylinders where the width is the minor diameter of the ellipse. The nanostructures may have other shapes such as square, rectangular or irregular cross-sections. The nanostructures may have a constant cross-section or may have a taper (e.g., narrower at the top than at the bottom or vice versa). The width can be understood to be the width where the nanostructure is widest along the length of the nanostructure.

The first nanostructures may be arranged in a substantially random pattern, a substantially ordered pattern, or in a partially ordered pattern, for example. In some cases, the first nanostructures may be approximately hexagonally packed posts (e.g., when a high density of posts are present). In some embodiments, the average spacing S1 is greater than the average width W1. In some embodiments, the average spacing S1 is at least 1.5 times, or at least 2 times or at least 3 times, or at least 4 times the average width W1. In some embodiments, the spacing and/or sizes of the nanostructures varies (e.g., randomly) over the nanostructured surface.

In some embodiments, the plurality of first nanostructures extend away from the substrate along a length of the first nanostructures where the plurality of first nanostructures have an average length L1 and an average width W1 with W1 being in a range of 5 nm to 500 nm, and L1/W1 being at least 1. W1 may be in a range of 10 nm to 300 nm, or 20 nm to 250 nm, for example. L1/W1 may be at least 2, 3, 5, 10, or 20, for example. For example, L1/W1 may be in a range of 1 to 100, or 1 to 50, or 3 to 20. L1 may be equal to an average height H1 of the first nanostructures (e.g., when the first nanostructures extend perpendicular to the substrate) or L1 may be greater than H1 (e.g., when the first nanostructures extend in a direction making an oblique angle to the substrate or when the first nanostructures extend irregularly from the substrate (see, e.g., FIG. 10)). L1 and/or H1 may be in a range of 10 to 500 nm, or 100 to 450 nm, or 150 nm to 400 nm, for example.

The nanostructured article 100 or 200 can be made by etching (e.g., plasma etching or reactive ion etching) as described further elsewhere herein. The nanostructured article 200 can be made by anisotropically etching generally along a direction parallel to the first nanostructures 203 using reactive ion etching, for example. In some embodiments, the layer etched to form the nanostructures 103 or 203 include a polyurethane or an ionomeric or nanocomposite material described elsewhere herein. In some embodiments, the mask used in the etching is retained in a top portion of the first nanostructures as described further elsewhere herein. For example, a thin, approximately horizontal inorganic discrete islands may be disposed at the top of the first nanostructures 103 or 203, or an inorganic nanoparticle may be disposed at the top of the first nanostructures 103 or 203, for example. The lengths of the first nanostructures 103 or 203 may be approximately constant or there may be a distribution of the lengths as described further elsewhere herein. In some embodiments, each nanostructure in at least a majority of the plurality of first nanostructures has a substantially same length (e.g., within 30%, or within 20% of a same length). In some embodiments, the plurality of first nanostructures has a distribution of nanostructure lengths such that at least one nanostructure in the plurality of first nanostructures has a length at least 1.5 times a length of at least one other nanostructure in the plurality of first nanostructures.

The substrates 105 or 205 may include a plurality of layers. For example, the substrate layer illustrated in FIGS. 1 or 2 may be the top or outer layer of a multilayer film substrate as described further elsewhere herein.

FIG. 3 is a schematic cross-sectional view of a nanostructured article 300 including a substrate 305 and a plurality of first nanostructures 303. The first nanostructures 303 include a lower portion 302 and an upper portion 306. The upper portion 306 may be or include an inorganic nanoparticle used to form the first nanostructures 303. For example, a monolayer of nanoparticles may be disposed on a substrate and used as an etching mask for forming the nanostructures 303 on the substrate. The use of a monolayer of nanoparticles as an etching mask is described in U.S. Pat. Appl. Pub. No. 2012/0012557 (David et al.) and in International Appl. Pub. No. 2018/080830 and corresponding U.S. Pat. Appl. Pub. No. 16/340472 filed October 17, 2017. In some embodiments, the monolayer of nanoparticles is provided in a binder which may be retained between the upper portion 306 and the lower portion 302. In such embodiments, the heights and lengths of the first nanostructures 303 may be approximately constant. The nanoparticles may be substantially randomly arranged in the nanolayer resulting in an irregular arrangement of the first nanostructures 303. The first nanostructures 303 may be characterized by an average height H1 (and/or an average length L1), an average width W1, and/or an average spacing S1 as described further elsewhere herein. FIG. 4 is a schematic cross-sectional view of a nanostructured article 400 including a substrate

405 and a plurality of first nanostructures 403. The first nanostructures 403 include a lower portion 402 and an upper portion 406. The upper portion 406 may be or include a nanoparticle used to form the first nanostructures 403 and the substrate 405 may include a plurality of the nanoparticles dispersed therein. A polymeric layer is a layer that include a continuous phase of organic polymeric material. A polymeric layer may include nonpolymeric filler (e.g., inorganic nanoparticles) dispersed in the continuous phase. In some embodiments, a polymeric layer may include a plurality of inorganic nanoparticles dispersed in a polymeric material to form a layer that is etched to form the first nanostructures 403 on the substrate 405. The nanoparticles act as an etch mask in forming the first nanostructures 403 as generally described in U.S. Pat. Appl. Pub. No. 2016/0370605 (David et al.). Typically, when nanostructures are formed in this way, the nanostructures have a distribution of heights (e.g., having an average height H1 and a standard deviation about the average height greater than an average width W1 of the nanostructures 403) and a distribution of spacings (e.g., having an average center-to-center spacing S1) may be irregular. In some embodiments, the nanocomposite material described elsewhere herein is etched so that the upper portion

406 is a metal oxide nanoparticle of the nanocomposite.

Nanoparticles used to make the first nanostructures in the embodiments illustrated in FIGS. 3-4 may be inorganic (e.g., metal oxide) nanoparticles such as silica. A polymeric layer including nanoparticles may be used to form the first nanostructures in the embodiment illustrated in FIG. 4, for example. The nanoparticles may be included in the polymeric layer at 1 to 40 volume percent, or 2 to 40 volume percent, or 3 to 30 volume percent, or 3 to 20 volume percent, for example. The nanoparticles may be included in the layer at 3 to 65, weight percent, for example, where the desired range may depend upon the particle size (e.g., 3 to 20 weight percent for 5 to 30 nanometer particles, 3 to 50 weight percent for 30 to 100 nanometer particles, or 5 to 65 weight percent for 100 to 500 nanometer particles). The layer including the nanoparticles may be a nanocomposite layer that includes at least one polymer, which includes a first polymer including (meth)acrylic acid monomer units, and surface modified metal oxide nanoparticles dispersed in the at least one polymer as described further elsewhere herein.

FIG. 5 is a schematic cross-sectional view of a nanostructured article 500 including a substrate 505 and a plurality of first nanostructures 503. The first nanostructures 503 include a lower portion 502 and an upper portion 506. For example, the first nanostructures 503 may be made by applying a thin, random, discontinuous masking layer to a major surface of a substrate by plasma chemical vapor deposition, for example, and etching via reactive ion etching, for example, as described in U.S. Pat. Appl. Pub. No. 2013/0038949 (David et al.) to form the first nanostructures 503 on the substrate 505. In this case, the upper portions 506 results from the discontinuous masking layer. The resulting heights (and/or lengths) of the first nanostructures 503 may be approximately constant and the resulting spacing between first nanostructures may be irregular. The first nanostructures 503 have an average height H1, and average center-to-center spacing S1 and an average width W1. The widths of the first nanostructures may be randomly distributed about the average width W1 and the spacings between nanostructures may be randomly distributed about the average spacing S1.

FIG. 6 is a schematic cross-sectional view of a nanostructured article 600 including a substrate 605 and a plurality of first nanostructures 603. The first nanostructures 603 include a lower portion 602 and an upper portion 606. For example, an inorganic masking layer may be deposited during etching as described in U.S. Pat. Appl. Pub. No. 2017/0067150 (David et al.). The resulting first nanostructures 603 have distributions of height, width, and spacing. An average height H1, average center-to-center spacing S1, and an average width W1 are indicated.

In some embodiments, a coating (e.g., a fluorinated and/or low surface energy coating) may be disposed over any of the nanostructured surfaces of FIGS. 1 to 6. Such low surface energy coatings may be applied by any suitable method, for example plasma assisted vapor deposition, solvent coating methods, dip coating methods or spray coating methods. Suitable coating materials are described elsewhere herein. In some cases, a glass like or Diamond Like Glass (DLG) layer (e.g., a thin carbon containing silica layer) can be deposited onto the nanostructured surface prior to coating with a low surface energy material. In some embodiments, a DLG layer is preferred due to its flexibility and robust adhesion, for example. Processes for depositing DLG layers are described in U.S Pat. Nos. 5,888,594 (David et al.); 9,340,683 (Jing et al.); 9,206,335 (Hager et al.); and 9,556,338 (Jing et al.), for example, and in U.S. Pat. Appl. Pub. Nos. 2010/0035039 (Jing et al.); 2016/0289454 (Jing et al.); and 2017/0045284 (Meuler et al.), for example. The DLG layer may conform to the nanostructured surface.

A conformal layer (e.g., a monolayer, a tie layer and/or a glass like or DLG layer) may be disposed over any of the nanostructured articles of FIGS. 1 to 6. An illustrative example is provided in FIG. 7 which is a schematic cross-sectional view of a nanostructured article 700 including a substrate 705 and a plurality of first nanostructures 703 disposed on, and extending away from, the substrate 705. A conformal layer 711 is disposed on the nanostructures 703 which include a lower portion 702 and an upper portion 706.

A fluorinated and/or low surface energy layer may be disposed over the conformal layer 711 or over the first nanostructures of an of FIG. 1-6 with or without including a conformal layer over the first nanostructures.

FIG. 8 is a schematic cross-sectional view of a nanostructured article 800 including a substrate 805, a plurality of first nanostructures 803 disposed on, and extending away from, the substrate 805, and a layer 801 (e.g., a fluorinated and/or low surface energy layer) disposed on the plurality of first nanostructures 803 and at least partially filling spaces between the first nanostructures to an average minimum height above the substrate 805 of H0 such that the layer 801 has a nanostructured surface 807 defined by, and facing away from, the plurality of first nanostructures 803. The nanostructured surface 807 may be defined by the first nanostructures 803 by coating the layer 801 onto the first nanostructures 803 such that the shape of the first nanostructures 803 results in the nanostructure of the surface 807. The layer 801 also has a nanostructured surface 819 opposite the nanostructured surface 807 and facing the first nanostructures 803. The nanostructured surface 807 includes a plurality of second nanostructures 808. The layer 801 has local minimum heights above the substrate 805 in spaces between the second nanostructures 808 and the average minimum height H0 is the average of the local minimum heights. In some embodiments, the average minimum height H0 is at least 30 nm, or at least 40 nm, or at least 50 nm. In some embodiments, H0 is no more than 250 nm, or no more than 200 nm, or no more than 150 nm. In some embodiments, the layer 801 is a polymer layer which may be a fluoropolymer layer. In some embodiments, the layer 801 is a covalently crosslinked fluorinated polymeric layer.

The first nanostructures 803 have an average height H1, an average width W1 and an average (e.g., center-to-center) spacing S1. The substrate 805 has a major surface 809 (planar portion of the top surface of the substrate 805) and the first nanostructures 803 extend from the major surface 809. The layer 801 may contact the major surface 809 or may contact a coating (e.g., glass like DLG coating) applied to the major surface 809 (alternatively, the coating on the major surface 809, if present, may be considered to be part of the substrate 805 so that the layer 801 contacts the substrate). The major surface may have a roughness (e.g., an Ra roughness) on the order of 1 to 10 nm, for example. In some embodiments, the layer 801 at least partially fills spaces between the first nanostructures from the substrate (e.g., from surface 809 or from a coating applied to surface 809) to an average minimum height above the substrate of H0. The nanostructured article 800 has a nanostructured surface 804 which includes the major surface 809 and the outer surface of the first nanostructures 803.

The nanostructured surface 807 includes a plurality of second nanostructures 808 which have an average peak to valley height H2, an average height H3 above the substrate 805, an average width W2, and an average spacing (e.g., center-to-center spacing) S2. It has been found that the layer 801 can improve the durability of nanostructured surface. In some embodiments, the thickness of the layer 801 in the regions between the first nanostructures is increased, reducing the peak-to-valley height H2. This may be desired in some embodiments for improved durability. It has been found that the height H2 in such embodiments can still be sufficient to provide a desired (super)hydrophobic (hydrophobic or superhydrophobic) or (super)omniphobic (omniphobic or superomniphobic) effect. In some embodiments, H2 is less than H1, or less than 0.95 H1, or less than 0.9 H1, or less than 0.8 H1, or less than 0.7 H1. In some such embodiments or in other embodiments, H2 is at least 0.1 H1, or at least 0.2 H1, or at least 0.3 H1. In some embodiments, H2 is about H1, or H2 is less than H1, or H2 is less than 0.7 H1, or H2 is less than 0.5 H1. In some embodiments, H2 is in a range of 0.5 to 0.7 times H1.

The relative thicknesses of H0 and H1, for example, may be different than schematically illustrated in FIG. 8. For example, a nanostructured article 900 with a reduced H2 and increased H0 relative to the nanostructured article 800 is schematically illustrated in FIG. 9. Elements 901, 903, 904, 905, 907, 908, 909, 919 correspond to elements 801, 803, 804, 805, 807, 808, 809, 819 respectively. The layers 801 and 901 can be applied as a coating which is subsequently dried and cured. The thickness H0 can be increased by using a coating with a higher solids concentration, for example. In some embodiments, the first nanostructures 803 (resp., 903) extend to an average height H1 from the substrate 805 (resp., 905) and have an average width W1, and the nanostructured surface 807 (resp., 907) includes a plurality of second nanostructures 808 (resp., 908) having an average peak-to- valley height H2 and an average width W2. In some embodiments, H2/W2 is no more than 0.95 H1/W1, or no more than 0.9 H1/W1, or no more than 0.8 H1/W1. In some such embodiments or in other embodiments, H2/W2 is at least 0.1 H1/W1, or at least 0.2 H1/W1, or at least 0.3 H1/W1. In some embodiments, L2/W2 is at least 1, 2, 3, 5, 10, or 20, for example. L2/W2 may be in a range of 1 to 100, or 1 to 50, or 3 to 20, for example.

In some embodiments, the plurality of first nanostructures form into groups partially clumped together before or during coating with the fluorinated and/or low surface energy layer. This can occur, for example, when the aspect ratio of the first nanostructures is high (e.g., at least 10 or at least 20) and the nanostructures extend irregularly (e.g., in directions that vary along the length of the nanostructures). This is schematically illustrated in FIG. 10 which is a schematic cross-sectional view of a nanostructured article 1000 including a substrate 1005, a plurality of first nanostructures 1003 disposed on, and extending away from, the substrate 1005, and a layer 1001 (e.g., a fluorinated and/or low surface energy layer) disposed on the plurality of first nanostructures 1003 and at least partially filling spaces between the first nanostructures to an average minimum height above the substrate 1005 of H0 such that the layer 1001 has a nanostructured surface 1007 defined by, and facing away from, the plurality of first nanostructures 1003. In the illustrated embodiment, some of the spaces between first nanostructures 1003 are completely filled with the layer 1001. The nanostructured surface 1007 includes a plurality of second nanostructures 1008. The layer 1001 has local minimum heights above the substrate 1005 in spaces between the second nanostructures 1008 and the average minimum height H0 is the average of the local minimum heights. In some embodiments, each second nanostructure in at least a majority (or at least 60%, or at least 70%, or at least 80%) of the second nanostructures 1008 partially surrounds a plurality of the first nanostructures 1003.

The first nanostructures 1003 have an average height H1 above the substrate 1005. In the illustrated embodiment, the first nanostructures 1003 have an average length (measured along an axis of the first nanostructures) greater than the average height H1 since at least some of the first nanostructures 1003 are curved along at least a portion of their length. The average peak-to-valley height H2, the average width W2 and the average spacing S2 between the second nanostructures 1008 are schematically illustrated. In some embodiments, W2 is at least 2, 4, 5, or 10 times an average width of the first nanostructures 1003. In some embodiments, S2 is at least 2, 4, or 5 times an average spacing of the first nanostructures 1003. In some embodiments, H2 is less than 0.7 H1 or less than 0.5 H1. In some embodiments, H2 is at least 40, 50, 60, 80, or 100 nm. In some such embodiments or in other embodiments, H2 is no more than 300 nm, or no more than 250 nm.

The first nanostructures of any of FIGS. 8-10 may include a polymeric lower portion and an inorganic upper portion as described further elsewhere herein. The first nanostructures may extend generally normally to the substrate or may extend generally along a direction making an oblique angle to the substrate. In some embodiments, a metal oxide nanoparticle (e.g., corresponding to upper portion 1106) is disposed between the covalently crosslinked fluorinated polymeric layer (e.g., corresponding to layer 901) and a top surface of each first nanostructure in at least a majority of the plurality of first nanostructures.

In some embodiments, the first nanostructures generally extend in a direction making an oblique angle with the substrate and a fluorinated and/or low surface energy layer is disposed over the first nanostructures. This is schematically illustrated in FIG. 11 which is a schematic cross-sectional view of nanostructured article 1100 which includes a layer 1101 (e.g., a covalently crosslinked fluorinated polymeric layer) which at least partially fills spaces between the first nanostructures 1103 (the layer 1101 contacts the major surface 1109 of the substrate 1105 or contacts a glass like or DLG-coated, for example, major surface of the substrate 1105) to an average minimum height H0 above the substrate 1105 (measured from the plane of the major surface 1109).

In the illustrated embodiment, the first nanostructures 1103 include a lower portion 1102, which may be a polymeric portion including polyurethane or which may be an ionomeric portion, and an upper portion 1106, which may include an inorganic nanoparticle (e.g., a surface modified metal oxide nanoparticle).

The layer 1101 has a nanostructured surface 1107 defined by the first nanostructures 1103. The nanostructured surface 1107 includes a plurality of second nanostructures 1108 having a peak-to-valley height H2, an average width W2, and an average spacing S2. H2 is measured along a direction (z- direction) perpendicular to substrate and W2 and S2 are measure along the plane of the substrate (x-y plane). In embodiments where the nanostructured article 1100 is disposed on anon-planar surface (e.g., a curved surface), the plane of the substrate can be taken to be a locally defined plane (e.g., the tangent plane at a point of interest).

A glass like or DLG layer or other tie layer may be disposed over the first nanostructures before the (e.g., covalently crosslinked fluorinated polymeric) layer is disposed on the first nanostructures. This is schematically illustrated in FIG. 12 which is a schematic cross-sectional view of an article 1200 including first nanostructures 1203 coated with a DLG or other thin glass like layer 1211 (e.g., a tie layer for promoting adhesion) and including a layer 1201 disposed on the coated first nanostructures 1203 and at least partially filling spaces between the first nanostructures to an average minimum height H0 above the substrate 1205 such that the polymeric layer has a nanostructured surface 1207 defined by, and facing away from, the plurality of first nanostructures 1203. The nanostructured surface 1207 includes a plurality of second nanostructures 1208. Elements 1202, 1203, 1205a, 1206, and 1211 may correspond to elements 702, 703, 705, 706, 711, respectively.

In some embodiments, a unitary member includes the substrate or an upper layer of the substrate and the first nanostructures or a lower portion of the first nanostructures. The substrates of the nanostructured articles of the present description may include more than one layer. For example, the substrate may be a multilayer film. In the embodiment illustrated in FIG. 12, the substrate 1205 includes an upper layer 1205a and a lower layer 1205b. In some embodiments, a unitary member 1277 includes the upper layer 1205a of the substrate 1205 and the lower portion 1202 of the first nanostructures 1203. In some embodiments, the substrate 1205 includes a film (e.g. a multilayer film; not illustrated in FIG. 12) with the lower layer 1205b coated onto the film and the upper layer 1205a coated onto the lower layer 1205b.

The first nanostructures (e.g., the first nanostructures of any of FIGS. 1-12) of the nanostructured article may include polyurethane or an ionomeric or nanocomposite material of the present disclosure. For example, in some embodiments, the first nanostructures are formed on a polyurethane layer such that the first nanostructures include polyurethane material from the polyurethane layer. As another example, in some embodiments, the first nanostructures are formed on an ionomeric or nanocomposite layer such that the first nanostructures include ionomeric or nanocomposite material from the ionomeric or nanocomposite layer. In some embodiments, the first nanostructures are formed in a hardcoat layer (which may be a polyurethane hardcoat) disposed on a polyurethane layer or on an ionomeric or nanocomposite layer. The polyurethane layer may be an energy dissipation layer and/or a shape memory layer.

A wide range of (meth)acrylic polymers are suitable for use in the nanocomposites or ionomers of this disclosure. The (meth)acrylic polymer(s) include (meth)acrylic acid monomers units (i.e., acrylic acid monomer units, methacrylic acid monomer units, or both acrylic acid monomer units and methacrylic acid monomer units). In some embodiments, the (meth)acrylic polymers are homopolymers of acrylic acid or methacrylic acid. In other embodiments, the (meth)acrylic polymers are copolymers of at least one (meth)acrylic monomer unit that is acid-functional and at least one monomer that is a (meth)acrylate that is not acid-functional. Additionally, the (meth)acrylic polymers can contain other non-(meth)acrylate monomers that are co-polymerizable with the (meth)acrylic and (meth)acrylate monomers. The copolymers can be formed by the polymerization or copolymerization using free radical polymerization techniques. In some embodiments, the at least one (meth)acrylic polymer includes a copolymer containing (meth)acrylic acid and at least one co-monomer. A wide range of co-monomers are suitable. Suitable co-monomers include ethylene, propylene, alkyl(meth)acrylates, aryl(meth)acrylates, alkaryl(meth)acrylates, acrylonitrile, and carbon monoxide.

In some embodiments, a nanocomposite includes at least one polymer and metal oxide nanoparticles dispersed in the at least one polymer of the nanocomposite. Each polymer can have a number average molecular weight of at least 10000 grams/mole. The at least one polymer of the nanocomposite includes a first polymer including (meth)acrylic acid monomer units (monomer units selected from the group consisting of methacrylic acid monomer units and acrylic acid monomer units). The metal oxide nanoparticles are surface modified with a surface modifying agent including a carboxylic acid silane of Formula 1 described elsewhere herein. In cases where an ionomer layer is desired, the metal oxide nanoparticles can be omitted. In some embodiments, the first polymer has a number average molecular weight of at least 12000 grams/mole or at least 15000 grams/mole. In some embodiments, each polymer of the at least one polymer has a number average molecular weight of at least 12000 grams/mole or at least 15000 grams/mole. For example, the at least one polymer can be a blend of first and second polymers, and each of the first and second polymers can have a number average molecular weight of at least 12000 grams/mole or at least 15000 grams/mole. The number average molecular mass of a polymer can be determined by gel permeation chromatography (GPC). Polymer characterization by GPC systems is well known. An example of such a system is the Viscotek TDAmax (Malvern Panalytical, a part of Spectris pic). This system is equipped with multiple detectors for determination of molecular weight. Absolute molecular weight of small polymers can be measured using a right angle light scattering detector, direct output of absolute molecular weight of polymers without extrapolation can be obtained using low angle light scattering. Additional detectors can be used to assess information concerning polymer structure, for example branching using intrinsic viscosity detector and information concerning copolymer composition can be investigated using a photodiode array UV detector when UV absorbing components are present. Further details of this instrument can be found from the supplier. In some embodiments, the first polymer, or each polymer of the at least one polymer, has a number average molecular weight less than 100,000 grams/mole.

In some embodiments, the first polymer further includes at least one monomer unit (e.g., a second type of monomer unit when the (meth)acrylic acid monomer units are a first type of monomer unit) selected from the group consisting of ethylene, propylene, alkyl(meth)acrylates, aryl(meth)acrylates, alkaryl(meth)acrylates, acrylonitrile, and carbon monoxide. In some embodiments, the first polymer includes at least one monomer unit (e.g., a second type of monomer unit) selected from the group consisting of ethylene and propylene. In some such embodiments, the first polymer further includes at least one monomer unit (e.g., a third type of monomer unit) selected from the group consisting of n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, n-propyl acrylate, ethyl acrylate, methyl acrylate, 2- ethylhexyl acrylate, iso-octyl acrylate and methyl methacrylate. The first polymer can be a terpolymer, for example. In some embodiments, the first polymer includes (meth)acrylic acid monomer units; ethylene monomer units, propylene monomer units, or a combination of ethylene and propylene monomer units; and at least one alkyl (meth)acrylate monomer unit. In some embodiments, the first polymer includes (meth)acrylic acid monomer units and ethylene monomer units.

The at least one polymer can be a blend of two or more (meth)acrylic polymers. A wide range of blends of (meth)acrylic polymers are suitable. Examples of suitable blends include blends of acrylic acid or methacrylic acid homopolymers with copolymers of acrylic acid or methacrylic acid and at least one additional monomer (e.g., selected from the group consisting of ethylene, propylene, alkyl(meth)acrylates, aryl(meth)acrylates, alkaryl(meth)acrylates, acrylonitrile, and carbon monoxide). Other examples include blends of acrylic acid or methacrylic acid homopolymers with copolymers of acrylic acid or methacrylic acid and at least two additional monomers (e.g., the copolymer can be a terpolymer). In some embodiments, the blends include a copolymer of acrylic acid or methacrylic acid and at least one additional monomer with a different copolymer of acrylic acid or methacrylic acid and at least one additional monomer. Yet other embodiments include blends of a copolymer of acrylic acid or methacrylic acid and at least one additional monomer with a copolymer of acrylic acid or methacrylic acid and at least two additional monomers. Additionally, the blend can also include different copolymers of acrylic acid or methacrylic acid and at least two additional monomers.

In some embodiments, the at least one polymer includes a second polymer different from the first polymer. The first and second polymers can be different by virtue of having different molecular weights, different acid content, different neutralization percent, different amounts of the same monomer units, and/or by being compositionally distinct, for example. In some embodiments, the second polymer is compositionally distinct from the first polymer. Compositionally distinct in this context can be understood to mean that at least one of the first and second polymers has a least one type of monomer unit not present in the other of the first and second polymers. For example, the first polymer can include two different monomer units (e.g., (meth)acrylic acid and either ethylene or propylene) and the second polymer can include a different third monomer unit (e.g., n-butyl acrylate or isobutyl acrylate) in addition to the two monomer units of the first polymer. Compositionally distinct includes different acid types (e.g., methacrylic acid monomer units versus acrylic acid monomer units) and different ion types (an ion at least partially neutralizing an ionomer can be considered to be part of the ionomer), for example. The second polymer can have a number average molecular weight of at least 10000 grams/mole, or at least 12000 grams/mole, or at least 15000 grams/mole.

In some embodiments, the second polymer includes (meth)acrylic acid monomer units. In some embodiments, the second polymer includes at least one monomer unit selected from the group consisting of ethylene, propylene, alkyl(meth)acrylates, aryl(meth)acrylates, alkaryl(meth)acrylates, acrylonitrile, and carbon monoxide. In some embodiments, the second polymer includes at least one monomer unit selected from the group consisting of ethylene and propylene. In some such embodiments, the second polymer further includes at least one monomer unit selected from the group consisting of n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, n-propyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, iso-octyl acrylate and methyl methacrylate. In some embodiments, the second polymer includes (meth)acrylic acid monomer units; ethylene monomer units, propylene monomer units, or a combination of ethylene and propylene monomer units; and at least one alkyl (meth)acrylate monomer unit. In some embodiments, the second polymer includes (meth)acrylic acid monomer units and ethylene monomer units.

In some embodiments, the content of (meth)acrylic acid monomer units in the first polymer, and optionally in the second polymer, is greater than 12 weight percent. This has been found to help in dispersing the first polymer, and optionally the second polymer, in water. In some embodiments, the content of (meth)acrylic acid monomer units in the first and the second polymers is similar. This has been found to help the compatibility of the polymers and to improve optical properties, for example. In some embodiments, the first polymer includes (meth)acrylic acid monomer units at a first weight percent w1, and the second polymer includes (meth)acrylic monomer units at a second weight percent w2. In some embodiments, at least one of w1 and w2 (w1, or w2, or each of w1 and w2) is greater than 12 weight percent, or greater than 13 weight percent, or greater than 14 weight percent, or greater than 15 weight percent. In some embodiments, at least one of w1 and w2 is less than 50 weight percent, or less than 30 weight percent, or less than 25 weight percent. In some such embodiments, or in other embodiments, |w1- w2| is less than 15 weight percent or less than 14 weight percent, or less than 12 weigh percent, or less than 10 percent, or less than 8 percent, or less than 7 weight percent, or less than 6 weight percent.

Smaller values of the difference |w1-w2| may be preferred when both the first and second polymers are formed from an aqueous dispersion, while larger values of the difference may be useful, in some embodiments, when the second polymer is added in a melt processing step.

In some embodiments, the nanocomposite is formed from an aqueous dispersion including the first and second polymers as described further elsewhere herein. In some such embodiments, or in other embodiments, each of w1 and w2 is greater than 12 weight percent, or greater than 13 weight percent, or greater than 14 weight percent, or greater than 15 weight percent. In some such embodiments, or in other embodiments, |w1-w2| is less than 10 weight percent, or less than 9 weight percent, or less than 8 weight percent, or less than 7 weight percent, or less than 6 weight percent. In some embodiments, |w1-w2| is in a range of 0 to 10 weight percent or in a range of 0 to about 9 weight percent (e.g., 8.8 or 9 or 9.2 weight percent can be considered to be about 9 weight percent). In some cases, where each of the two polymers in dispersion includes two monomer units (e.g., a (meth)acrylic acid monomer unit and a second monomer unit such as ethylene or propylene), the acid content of either the first polymer (w1) or second polymer (w2) may be in a range greater than 27 weight percent, for example. When one of the two polymers (e.g., the first polymer) has an acid content of greater than 27%, the difference |w1-w2| may be up to 15 weight percent, for example.

In some embodiments, a first nanocomposite, or a first concentrated aqueous dispersion, that includes the first polymer is melt processed with the second polymer (also referred to as an additional polymer) to form a nanocomposite (e.g., a second nanocomposite) that includes both the first and second polymers. In some such embodiments, the second polymer is not dispersible in water with or without a neutralizing agent. In some embodiments, w2 can be less than 12 weight percent and/or |w1-w2| can be as high as 15 weight percent, for example. In some embodiments, w1 is greater than 12 weight percent, or greater than 13 weight percent, or greater than 14 weight percent, or greater than 15 weight percent; or in a range of 13 to 50 weight percent, or 13 to 35 weight percent, or 13 to 27 weight percent, or 14 to 22 weight percent, or 15 to 21.5 weight percent, or 15 to 21 weight percent, or 15 to 20.5 weight percent. In some such embodiments, or in other embodiments, w2 is at least 10 weight percent; or in a range of 10 weight percent to 25 weight percent, or to 21.5 weight percent, to 21 weight percent, or to 20.5 weight percent; or w2 can be in any range described for w1. For example, in some embodiments, w1 is in a range of 15 to 20.5 weight percent and w2 is in a range of 10 to 20.5 weight percent or 15 to 20.5 weight percent. In some embodiments, at least one of w1 and w2 is in a range of 14 to 22 weight percent or in a range of 15 to 21.5 weight percent.

In some embodiments, the first polymer includes (meth)acrylic acid monomer units at a weight percent w1 and further includes ethylene monomer units, and the second polymer includes (meth)acrylic acid monomer units at a weight percent w1 and further includes ethylene monomer units. In some such embodiments, w1 is greater than 15 weight percent, and |w1-w2| is less than 10 weight percent.

In some embodiments, the first polymer includes (meth)acrylic acid monomer units at a weight percent w1 and further includes ethylene monomer units, and the second polymer includes (meth)acrylic acid monomer units at a weight percent w1, and further includes ethylene monomer units, and further includes at least one monomer unit selected from the group consisting of n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, n-propyl acrylate, ethyl acrylate, methyl acrylate, 2-ethylhexyl acrylate, iso- octyl acrylate and methyl methacrylate. In some such embodiments, w1 is greater than 15 weight percent, and |w1-w2| is less than 15 weight percent, or less than 13 weight percent, or less than 12 weight percent.

In some embodiments, the first polymer is at least partially neutralized. By this it is meant that the first polymer includes a carboxylic acid group where the proton of the carboxylic acid group is replaced by a cation, such as a metal cation. Monovalent, divalent, and higher valency cations are suitable. In some embodiments, the first polymer is at least partially neutralized with metal cations, alkylammonium cations, or a combination thereof. In some embodiments, the first polymer is at least partially neutralized with sodium cations, calcium cations, potassium cations, zinc cations, lithium cations, magnesium cations, aluminum cations, or a combination thereof. In some embodiments, the first polymer is at least partially neutralized with nonmetallic cations. For example, the first polymer can be at least partially neutralized with alkylammonium cations. In some embodiments, the nanocomposite is formed from an aqueous dispersion as described further elsewhere herein. In some embodiments, in the aqueous dispersion, the first polymer is at least partially neutralized with at least one nonvolatile neutralizing agent, or at least one volatile neutralizing agent, or a combination of volatile and nonvolatile neutralizing agents. For example, in some embodiments, in the aqueous dispersion, the first polymer is at least partially neutralized with nonvolatile amine cations, volatile amine cations (e.g., cations of dimethylethanolamine or ammonium cations), or a combination of volatile and nonvolatile amine cations. The first polymer can be at least partially neutralized with a combination of different types of cations (e.g., metallic and nonmetallic cations or any combinations of cations describe herein). The first polymer can be an at least partially neutralized ionomer prior to being dispersed in the aqueous dispersion. In some embodiments, the ionomer is sufficiently neutralized that no additional neutralizing agents need to be added to the aqueous dispersion. In other embodiments, the ionomer is further at least partially neutralized by additional neutralizing agents added to the aqueous dispersion as described further elsewhere herein.

In some embodiments, the second polymer is at least partially neutralized. In some embodiments, each polymer of the at least one polymer, or each polymer including (meth)acrylic acid monomer units, is at least partially neutralized. The second polymer, or other polymers of the at least one polymer, can be at least partially neutralized with any cation or combination of cations described for the first polymer.

Suitable ethylene (meth)acrylic acid copolymers can be obtained from commercial sources such as PRIMACOR 5980i from SK Global Chemical Co., Ltd. (Seoul, South Korea), NUCREL 925 and 960 from Dow Chemical Co. (Midland, MI)„ ESCOR 5200 from Exxon-Mobil (Irving, TX), and AC-5180 from Honeywell (Morris Plains, NJ), for example. Suitable partially neutralized ethylene (meth)acrylic acid copolymers can be obtained from commercial sources such as, for example, SURLYN 1601, 1706, 1707, 7940, 9020, 9120, 8150 and PC-350, and HPF 1000 from Dow Chemical Co. (Midland, MI), for example.

A wide range of metal oxide nanoparticles are suitable. Examples of suitable metal oxide nanoparticles include metal oxides of silicon (silicon is considered to be a metalloid and thus is included in the list of metal oxides), titanium, aluminum, hafnium, zinc, tin, cerium, yttrium, indium, antimony or mixed metal oxides thereof. Among the more desirable metal oxide nanoparticles are those of silicon. For example, the metal oxide nanoparticles can be silica (SiO₂) nanoparticles or SiOx (0 < x < 2) nanoparticles.

The size of such particles can be chosen to avoid significant visible light scattering. The surface- modified metal oxide nanoparticles can be particles having a (e.g. unassociated) primary particle size or associated particle size of greater than 1 nm (nanometers) and less than 450 nm or less than 200 nm. In some embodiments, the particle size is greater than 4 nm, greater than 5 nm, greater than 10 nm, or greater than 20 nm. In some embodiments, the particle size is less than 190 nm, less than 150 nm, less than 100 nm, less than 75 nm, or less than 50 nm. Typically, the nanoparticles have a size ranging from 4- 190 nm, 4-100 nm, 4-75 nm, 10-50 nm, or 20-50 nm. In embodiments where a low optical haze is desired, a particle size of less than 100 nm, less than 75 nm, or less than 50 nm is typically preferred. When the nanoparticles are used as an etch mask as described further elsewhere herein (see, e.g., FIG. 4 where the upper portions 406 can be the surface modified metal oxide nanoparticles), the nanoparticles may have a size ranging from 10 nm to 440 nm, or 10 nm to 150 nm, or 10 nm to 90 nm, for example. It is typically desirable that the nanoparticles are unassociated. Particle size can be measured in a wide variety of ways such as by transmission electron microscopy (TEM). Typically, commercially obtained metal oxide nanoparticles are supplied with a listed particle size or particle size range.

The nanoparticles are surface modified to improve compatibility with the polymer matrix material and to keep the nanoparticles non-associated, non-agglomerated, non-aggregated, or a combination thereof. The surface modification used to generate the surface-modified nanoparticles includes at least one acid-functional silane surface modifying agent. The acid-functional silane surface modifying agent can have the general Formula 1 :

where R1 is a C₁ to C₁₀ alkoxy group; and R2 and R3 are independently selected from the group consisting of C₁ to C₁₀ alkyl and C₁ to C₁₀ alkoxy groups. The group A is a linker group selected from the group consisting of C₁ to C₁₀ alkylene or arylene groups, C₁ to C₁₀ aralkylene groups, C₂ to C₁₆ heteroalkylene or heteroarylene groups, and C₂ to C₁₆ amide containing groups. Amide containing groups include groups of the type -(CH₂)_a-NH-(CO)-(CH₂)_b-; where a and b are integers of 1 or greater, and (CO) is a carbonyl group C=O. In some embodiments, A is an alkylene group with 1-3 carbon atoms.

While acid-functional silanes may be commercially available, one aspect of the current disclosure includes the synthesis of the carboxylic acid-functional silanes of Formula 1. In addition to the synthetic process presented below, an anhydride -functional silane such as (3-triethoxysilyl)propylsuccinic anhydride, which can be obtained from commercial sources such as Gelest, Inc. (Morrisville, PA), could be used to prepare the acid-functional silane surface modification agent.

In some embodiments, a solution is prepared of an organic acid anhydride dissolved in a first organic solvent. A second solution is prepared of an aminosilane in a second organic solvent. The two solutions are combined. The combined solution is stirred continuously at a suitable temperature and duration to synthesize a carboxylic acid-functional silane of Formula 1. In other embodiments, a solution is prepared of an organic acid anhydride dissolved in an organic solvent. An aminosilane is dissolved in the organic acid anhydride solution. The solution containing the organic acid anhydride and aminosilane is stirred continuously at a suitable temperature and duration to synthesize a carboxylic acid silane of Formula 1. The first and second organic solvents may be the same or different. In the case where the first and second organic solvent are different, then the first and second organic solvents are miscible. Both first and second organic solvents are miscible with water.

Suitable organic acid anhydrides include succinic anhydride (3,4-dihdrofuran-2,5-dione), tetrahydrofuran-2,5-dione, 3-alkyltetrahydrofuran-2,5-diones such as 3-methyltetrahydrofuran-2,5-dione and 3-ethyltetrahydrofuran-2,5-dione, tetrahydropyran-2,6-dione, 3-alkyltetrahydropyran-2,6-diones such as 3-methyltetrahydropyran-2,6-dione and 3-ethyltetrahydropyran-2,6-dione 4-alkyltetrahydropyran-2,6- diones such as 4-methyltetrahydropyran-2,6-dione, 4-ethyltetrahydropyran-2,6-dione, and 4,4'- methyltetrahydropyran-2,6-dione, oxepane-2,7-dione. Suitable organic acid anhydrides can be obtained from commercial sources such as Alfa Aesar (Ward Hill, MA) and Millipore Sigma (Burlington, MA). Succinic anhydride is a particularly suitable organic acid anhydride.

Suitable aminosilanes include aminopropyltrimethoxysilane, aminopropyltriethoxy silane, p- aminophenyltrimethoxy silane, p-aminophenyltriethoxysilane, N-phenylaminopropyltrimethoxysilane, N- phenylaminopropyltriethoxysilane, n-butylaminopropyltrimethoxysilane, n- butylaminopropyltriethoxy silane, 3-(N-allylamino)propyltrimethoxysilane, (N,N-diethyl-3- aminopropyl)trimethoxysilane, and (N,N-diethyl-3-aminopropyl)triethoxysilane. Suitable aminosilanes can be obtained from commercial sources such as Gelest, Inc. (Morrisville, PA), Alfa Aesar (Ward Hill, MA), Millipore Sigma (Burlington, MA), and Momentive Performance Materials (Waterford, NY). A particularly suitable aminosilane is aminopropyltrimethoxysilane.

A wide variety of organic solvents can be used. Suitable organic solvents include N,N- dimethylformamide (DMF) which can be obtained from commercial sources such as OmniSolv (Billerica, MA).

In some embodiments, the surface -modified metal oxide nanoparticles are prepared by combining an aqueous nanodispersion of surface unmodified metal oxide nanoparticles of basic pH and a carboxylic acid-functional silane surface modifying agent, reacting the carboxylic acid-functional silane surface agent with the metal oxide nanoparticle surface resulting in an aqueous nanodispersion of surface- modified metal oxide nanoparticles where the nanoparticles are surface modified with a carboxylic acid. This can be carried out in a variety of ways. In some embodiments, an aqueous nanodispersion of surface unmodified metal oxide nanoparticles is combined with a solution of a carboxylic acid silane of Formula 1 in an organic solvent. In other embodiments, an aqueous nanodispersion of surface unmodified metal oxide nanoparticles is combined with a base and a solution of a carboxylic acid silane of Formula 1 in an organic solvent. In other embodiments, an aqueous nanodispersion of surface unmodified metal oxide nanoparticles is combined with a carboxylic acid silane of Formula 1. Generally, the carboxylic acid silane of Formula 1 is added at a concentration sufficient to modify 10 to 100% of the total metal oxide nanoparticle surface area in the nanodispersion. As was mentioned above, the metal oxide nanoparticles may have a variety of sizes. Typically, the average particle size is greater than 1 nm and less than 450 nm, or less than 200 nm. In some embodiments, the particle size is greater than 4 nm, greater than 5 nm, greater than 10 nm, or greater than 20 nm. In some embodiments, the particle size is less than 190 nm, less than 150 nm, less than 100 nm, less than 75 nm, or less than 50 nm. Typically, the nanoparticles have a size ranging from 4-190 nm, 4-100 nm, 4-75 nm, 10-50 nm, or 20-50 nm. For low haze, typical preferred ranges are from 4-100 nm, 4-75 nm, or 4-50 nm. When the nanoparticles are used as an etch mask as described further elsewhere herein, a larger nanoparticle size (e.g., up to 440 nm, or up to 190 nm, or up to 90 nm) size may be used. In some cases, a base may be added to the aqueous nanodispersion of surface unmodified metal oxide nanoparticles to maintain the pH in the desired range since the addition of the carboxylic acid silane solution of Formula 1 will tend to lower pH. In some cases, the organic solvent is removed from of the solution of carboxylic acid silane in organic solvent prior to combining the carboxylic acid silane and aqueous nanodispersion of surface unmodified metal oxide nanoparticles.

Aqueous nanodispersions of unmodified metal oxide nanoparticles may be prepared or, in some embodiments, aqueous nanodispersions of unmodified metal oxide nanoparticles may be obtained commercially. Suitable surface unmodified metal oxide nanoparticles include aqueous nanodispersions commercially available from Nalco Chemical Company (Naperville, IL) under the trade designation ‘Nalco Colloidal Silicas” such as products NALCO 2326, 1130, DVSZN002, 1142, 2327, 1050, DVSZN004, 1060, and 2329K; from Nissan Chemical America Corporation (Houston, TX) under the tradename SNOWTEX such as products ST-NXS, ST-XS, ST-S, ST-30, ST-40, ST-N40, ST-50, ST-XL, and ST-YL; from Nyacol Nano Technologies, Inc. (Ashland, MA) such as NEXSIL 5, 6, 12, 20, 85-40, 20A, 20K-30, and 20NH4. In some cases, the surface unmodified metal oxide nanoparticles may be dispersed in an aqueous solution with a pH in the range 8-12.

Suitable bases include ammonium hydroxide which can be obtained from commercial sources such as Millipore Sigma (Burlington, MA).

Typically, the surface-modified metal oxide nanoparticles are used as a nanodispersion, and the particles are not isolated. Another aspect of the present disclosure involves the preparation of nanodispersions of surface-modified metal oxide nanoparticles without precipitation, gelation, agglomeration, or aggregation, where the metal oxide nanoparticles are surface modified with a carboxylic acid silane of Formula 1.

In some embodiments, an aqueous nanodispersion of surface unmodified metal oxide nanoparticles and solution of a carboxylic acid silane of Formula 1 in an organic solvent are combined in a reactor and heated at a suitable temperature and duration to react the carboxylic acid silane of Formula 1 with the surface of the metal oxide nanoparticles. In other embodiments, an aqueous nanodispersion of surface-unmodified metal oxide nanoparticles, base, and a solution of carboxylic acid silane of Formula 1 in an organic solvent are combined in a reactor and heated at a suitable temperature and duration to react the carboxylic acid silane of Formula 1 with the surface of the metal oxide nanoparticles. In some embodiments, a solvent exchange is performed on the aqueous nanodispersion of surface-modified metal oxide nanoparticles and organic solvent to remove the organic solvent. In some embodiments, the reactor is open, under reflux conditions, and in other embodiments the reactor is closed and under pressure. In some embodiments, the reactor is glass and in some embodiments the reactor is stainless steel.

A wide range of loadings of the surface-modified metal oxide nanoparticles in the nanocomposite are suitable. Typically, the nanocomposite includes at least 1% by weight of surface-modified metal oxide nanoparticles and no more than 70% by weight of surface-modified metal oxide nanoparticles. In some embodiments, the surface-modified metal oxide nanoparticle concentration is from 3-60% by weight, or from 3-50% by weight.

Additional additives may include flame retardants, thermal stabilizers, anti-slip agents, neutralizing agents, UV absorbers, light stabilizers, antioxidants, crosslinking agents, mold release agents, catalysts, colorants, anti-stat agents, defoamers, plasticizers, and other processing aids, for example.

An aqueous dispersion can be used in forming the nanocomposite or ionomer layers without nanoparticles. It has been unexpectedly found that high molecular weight (meth)acrylic polymer(s) (e.g., number average molecular weight of at least 10000 grams/mole) can be dispersed in water (e.g., with suitable neutralizing agents) and that the resulting aqueous dispersion is useful in making a nanocomposite, for example, with desired mechanical and optical properties. In some embodiments, an aqueous dispersion includes water; at least one polymer dispersed in the water; and metal oxide nanoparticles dispersed in the water. The at least one polymer includes a first polymer including (meth)acrylic acid monomer units and optionally having a number average molecular weight of at least 10000 grams/mole. The first polymer is at least partially neutralized. The metal oxide nanoparticles are surface modified with a carboxylic acid silane surface modifying agent. The carboxylic acid silane surface modifying agent can be or include a carboxylic acid silane of Formula 1, described elsewhere herein. The metal oxide nanoparticles can optionally be omitted when an ionomer layer not including nanoparticles is desired.

In some embodiments, a nanostructured article includes at least one polyurethane layer. The polyurethane may be or include a solvent-based or water-based polyurethane, a melt processed thermoplastic polyurethane, a crosslinked thermoset polyurethane (e.g. a polyurethane containing siloxane groups), or an ultraviolet (UV) curable polyurethane (e.g. an acrylate). In some embodiments, the polyurethane is a polyester-based polyurethane, a polycarbonate-based polyurethane or a combination or blend of both. The water-based polyurethane can be made from an aqueous-based polyurethane dispersion (i.e., PUD), and the solvent-based polyurethane can be made from a solvent-based polyurethane solution (i.e., PUS). Typically, the water and solvent, i.e. liquid, is removed from the polyurethane coating solution to form a polyurethane coating or film. Optionally, the polyurethane may be cured during the liquid removal step and/or after liquid removal, enhancing the properties of the polyurethane coating or film. In some preferred embodiments, the polyurethane is a covalently crosslinked polyurethane. Covalently crosslinked polyurethanes can provide desired chemical resistance and mechanical robustness (e.g., scratch or abrasion or impact resistant). In some such embodiments or in other embodiments, the polyurethane is a covalently crosslinked aliphatic polyurethane and/or a covalently crosslinked urethane acrylate. Suitable polyurethane materials are described in U.S. Pat. Appl. Pub. Nos. 2017/0170416 (Johnson et al.) and 2017/016590 (Leatherdale et al.), for example.

The polyurethane may be characterized in terms of a storage modulus E' (Young's modulus), a loss modulus E", and/or a ratio (tan δ (tan delta) or loss tangent) of the loss modulus E" to the storage modulus E'. The polyurethane layer may have energy dissipating properties and can have a tan δ peak value of at least 0.5, or at least 0.8 or greater, or at least 1.0, or at least 1.2, or at least 1.4, or from 0.5 to 2.5, or from 1 to 2.5, or from 1 to 2. In some embodiments, tan δ at room temperature (e.g., 20 °C) is at least 0.5, or at least 1, or at least 1.2, or at least 1.4. In some such embodiments, the tan δ at room temperature is no more than 2. The polyurethane can have a Young's modulus (E') greater than 0.4 MPa, greater than 0.6 MPa, or greater than 0.9 MPa over the temperature range -40 °C to 70 degrees °C.

The modulus and tan δ can be determined by dynamical mechanical analysis (DMA), for example. In some embodiments, the modulus and tan δ are determined according to the ASTM D4065-12 or D5026-15 test standards, for example. An oscillation of 0.2 percent strain at 1 Hz throughout a temperature ramp from -50 deg. C to 200 deg. C at rate of 2 deg. C per minute can be used to measure the glass transition temperature, the moduli and the peak tan δ.

In some embodiments, it is desired that the nanostructured article be bendable so that it can conform to a curved surface, for example. In such embodiments, it may be desired that the polyurethane has a suitable elongation to yield and/or elongation at break that allows a suitable bendability or foldability. In some embodiments, the elongation at yield and/or the elongation at break is at least 2%, or at least 3%, or at least 5%, or at least 7%, or at least 10%, or at least 15%, or at least 25%, or at least 50%.

In some embodiments, the polyurethane layer is a covalently crosslinked polyurethane layer. The covalently crosslinked polyurethane layer can include chemically, or covalently crosslinked materials derived from step growth polymerization of isocyanate and polyol oligomers. Selection of reactant isocyanates and polyols may modify the glass transition temperature of the resulting cured polyurethane. The crosslinked polyurethane layer may be coated onto a substrate (e.g., a polymeric substrate) or glass layer (that may be primed) and then be cured or crosslinked to form a thermoset polyurethane layer. The crosslinked polyurethane layer may then be coated with an aqueous dispersion that is then dried to form an ionomeric or nanocomposite layer of the present disclosure. Alternatively, the crosslinked polyurethane layer can be produced as a film, or as a layer of a film that also includes an ionomeric or nanocomposite layer, that is then laminated to a substrate or glass layer in a subsequent process step. Such lamination could be assisted with heat, or vacuum, or through the use of an adhesive, or a combination thereof. The substrate or glass layer may be substantially transparent (e.g., an average optical transmittance of at least 60%, or at least 70%, or at least 80%, or at least 90%).

Polyurethane generally refers to a polymer including organic units joined by carbamate (urethane) links. The polyurethanes described herein are typically thermosetting polymers that do not melt when heated. Polyurethane polymers may be formed by reacting a di- or polyisocyanate with a polyol. Both the isocyanates and polyols used to make polyurethanes contain on average two or more functional groups per molecule. The polyurethanes may have a functionality greater than 2.4 or 2.5.

A wide variety of polyols may be used to form a crosslinked polyurethane. The term polyol includes hydroxyl-functional materials that generally include at least 2 terminal hydroxyl groups. Polyols include diols (materials with 2 terminal hydroxyl groups) and higher polyols such as triols (materials with 3 terminal hydroxyl groups), tetraols (materials with 4 terminal hydroxyl groups), and the like. Typically, the reaction mixture contains at least some diol and may also contain higher polyols. Higher polyols are useful for forming crosslinked polyurethane polymers. Diols may be generally described by the structure HO — B — OH, where the B group may be an aliphatic group, an aromatic group, or a group containing a combination of aromatic and aliphatic groups and may contain a variety of linkages or functional groups, including additional terminal hydroxyl groups. In some embodiments, for example, where optical performance and material optical stability is desired, aliphatic crosslinked polyurethane may be preferred. In other embodiments, aromatic polyurethane may be used. Polyester polyols are useful for forming crosslinked polyurethane polymers. Among the useful polyester polyols are linear and non-linear polyester polyols including, for example, polyethylene adipate, polybutylene succinate, polyhexamethylene sebacate, polyhexamethylene dodecanedioate, polyneopentyl adipate, polypropylene adipate, polycyclohexanedimethyl adipate, and poly ε-caprolactone. Suitable aliphatic polyester polyols include those available from King Industries, Norwalk, CT, under the trade name “K-FLEX” such as K-FLEX 188 or K-FLEX A308.

A wide variety of polyisocyanates may be used to form the aliphatic crosslinked polyurethane. The term polyisocyanate includes isocyanate-functional materials that generally include at least 2 terminal isocyanate groups. Polyisocyanates include diisocyanates (materials with 2 terminal isocyanate groups) and higher polyisocyanates such as triisocyanates (materials with 3 terminal isocyanate groups), tetraisocyanates (materials with 4 terminal isocyanate groups), and the like. Typically, the reaction mixture contains at least one higher isocyanate if a difunctional polyol is used. Higher isocyanates are useful for forming crosslinked polyurethane polymers. Diisocyanates may be generally described by the structure OCN — Z — NCO, where the Z group may be an aliphatic group, an aromatic group, or a group containing a combination of aromatic and aliphatic groups.

Higher functional polyisocyanates, such as triisocyanates, are useful to form a crosslinked polyurethane polymer. Triisocyanates include, for example, polyfunctional isocyanates, such as those produced from biurets, isocyanurates, or adducts, for example. Some commercially available polyisocyanates include portions of the DESMODUR and MONDUR series from Covestro (Leverkusen, Germany), and the PAPI series from Dow Plastics, a business group of the Dow Chemical Company, Midland, MI. Useful triisocyanates include those available from Covestro under the trade designations DESMODUR N3300A and MONDUR 489.

The reactive mixture used to form the aliphatic crosslinked polyurethane typically also contains a catalyst. The catalyst facilitates the step-growth reaction between the polyol and the polyisocyanate. Conventional catalysts generally recognized for use in the polymerization of urethanes may be suitable for use with the present description. For example, aluminum-based, bismuth-based, tin-based, vanadium- based, zinc-based, or zirconium-based catalysts may be used. Tin-based catalysts may be preferred in some embodiments. Tin-based catalysts have been found to significantly reduce the amount of outgassing present in the polyurethane. Most desirable are dibutyltin compounds, such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin diacetylacetonate, dibutyltin dimercaptide, dibutyltin dioctoate, dibutyltin dimaleate, dibutyltin acetonylacetonate, and dibutyltin oxide. For example, the dibutyltin dilaurate catalyst DABCO T-12, commercially available from Air Products and Chemicals, Inc., Allentown, PA is suitable. The catalyst is typically included at levels of at least 200 ppm or even 300 ppm or greater. The catalyst may be present in the final formed films at levels of at least 100 ppm or in a range from 100-500 ppm, for example.

The covalently crosslinked polyurethane may have a crosslink concentration of at least 0.1 mol/kg, or at least 0.2 mol/kg, or at least 0.3 mol/kg, or at least 0.34 mol/kg. In some such embodiments, the crosslink concentration is no more than 1.2 mol/kg, or no more than 1.05 mol/kg, or no more than 1 mol/kg, or no more than 0.9 mol/kg, or no more than 0.75 mol/kg, or no more than 0.65 mol/kg. In some embodiments, the covalently crosslinked polyurethane has a crosslink concentration in a range of 0.2 to 1.2 mol/kg. In some preferred embodiments, the covalently crosslinked polyurethane has a crosslink concentration in a range of 0.3 to 1.05 mol/kg.

The crosslink concentration and the gel content of the cured polyurethane can be calculated using the method described in Macromolecules, Vol. 9, No. 2, pages 206-211 (1976). To implement this model, integral values for chemical functionality are used. DESMODURN3300 is reported to have an average functionality of 3.5 and an isocyanate equivalent weight of 193 g/equiv. This material was represented in the mathematical model as a mixture of 47.5 wt% HDI trimer (168.2 g/equiv.), 25.0 wt% HDI tetramer (210.2 g/equiv.), and 27.5 wt% of HDI pentamer (235.5 g/equiv.). This mixture yields an average equivalent weight of 193 g/equiv. and an average functionality of 3.5. Desmodur N3400 is reported to have an average functionality 2.5 and an equivalent weight of 193, and it is reported to be blend of the HDI isocyanurate trimer and HDI uretdione dimer. This material was represented in the mathematical model as a mixture of 19 wt% HDI isocyanurate trimer, 33 wt% HDI uretdione dimer, and 10 wt% of HDI uretdione trimer and 38 wt% of HDI tetramer having one isocyanurate group and one uretdione group. In the mathematical model, the functionality was determined by the sum the isocyanate groups and the uretdione groups in the cases where there was an excess of hydroxyl groups relative to the sum of the isocyanate and uretdione groups.

To produce a polyurethane layer with a glass transition temperature below 10 °C, it can be preferable to limit the amount of the isocyanate component. In some embodiments using HDI-derived isocyanates, it can be preferable to use less than 40 wt% isocyanate component based on the total core layer composition, or less than 38 wt%, or less than 35 wt%. In some embodiments, it is preferable to use an isocyanate component containing uretdione groups. When uretdione groups are included, it can be preferable to use an excess of hydroxyl functional groups relative to isocyanate groups. The excess hydroxyl groups can react with the uretdione groups to form allophanate groups to provide cure and chemical crosslinking. In some embodiments, it is preferable to include only a single polyol component to produce a narrow tan δ peak. In some embodiments, it is preferable to use a polyol component and an isocyanate component that are miscible with each other at room temperature.

The polyurethane may be formed with urethane acrylate oligomers. Urethane acrylate oligomers may be formed from a wide variety of urethane materials with acrylate or methacrylate reactive groups. Urethane acrylate oligomers are commercially available from vendors such as, for example, Sartomer of Exton, PA (a subsidiary of Arkema) and ALLNEX. Suitable aliphatic urethane oligomers include, for example, CN9002, CN9004, CN9893, CN9010 and CN3211 available from Sartomer Company and those available from ALLNEX under the EBECRYL brand name. The urethane acrylate oligomers may be aliphatic or aromatic. In some embodiments, aliphatic is preferred. The polyurethane may be formed by mixing the polyurethane precursor components with polyacrylate precursor components. The polyurethane and the polyacrylate polymers can be formed via distinct initiators. This allows the polyacrylate polymer to be selectively formed without forming the polyurethane polymer. The polyurethane polymer may be formed with the use of a catalyst (thermal curing) and the polyacrylate may be formed with the use of a photoinitator (UV or light curing), for example.

The precursor (containing both the polyurethane precursor components with the polyacrylate precursor components with both photoinitiator and catalyst) may be coated onto the polymeric substrate layer (that may be primed) or the glass layer and then the polyacrylate polymer may be selectively polymerized or cross-linked (via UV curing) to form a b-stage layer. Then this b-stage layer can be cured or cross-linked to form the thermoset or crosslinked polyurethane polymer.

In some embodiments, the polyurethane layer contains a blend of polyacrylate polymer and crosslinked polyurethane polymer. The polyurethane layer, or a continuous polymeric phase of the polyurethane layer, may contain from 1 to 49 wt% polyacrylate polymer. The polyurethane layer, or a continuous polymeric phase of the polyurethane layer, may contain from 51 to 99 wt% crosslinked polyurethane polymer. The polyurethane layer, or a continuous polymeric phase of the polyurethane layer, may contain from 1 to 20 wt% polyacrylate polymer, or from 2 to 15 wt% polyacrylate polymer, or from 3 to 10 wt% polyacrylate polymer. The polyurethane layer, or a continuous polymeric phase of the polyurethane layer, may contain from 80 to 99 wt% crosslinked polyurethane polymer, or from 85 to 98 wt% crosslinked polyurethane polymer, or from 90 to 97 wt% crosslinked polyurethane polymer. The polyurethane layer may contain both a photoinitiator and a catalyst.

When the polyurethane layer contains less than about 10 wt% polyacrylate (based on wt% of polyacrylate precursor material in the precursor mixture), it is believed that the polyacrylate defines a mainly a linear or branched polymer. When the polyurethane layer contains about 10 wt% to about 20 wt% polyacrylate (based on wt% of polyacrylate precursor material in the precursor mixture), it is believed that the polyacrylate defines a branched or crosslinked polymer. When the polyurethane layer contains about 20 wt% to about 50 wt% polyacrylate (based on wt% of polyacrylate precursor material in the precursor mixture), it is believed that the polyacrylate defines mainly a crosslinked polymer. Crosslinked polyacrylate may define an interpenetrating network with the crosslinked polyurethane in the polyurethane layer.

The polyacrylate polymer is polymerized or crosslinked. The polyacrylate polymer may be formed of acrylate monomers or oligomers. In some embodiments, the polyacrylate is a polyacrylate homopolymer. The acrylate monomers or oligomers are multifunctional to enable polymerization or cross-linking of the polyacrylate polymer. The polyacrylate polymer may be formed with the aid of an initiator, such as a photo-initiator, for example. The polyacrylate polymer may be formed of oligomers that include acrylate and urethane segments, or acrylate and urethane compatible segments. The polyacrylate polymer may be aliphatic. The polyacrylate polymer may be formed of multifunctional (meth)acrylic monomers, oligomers, and polymers, where the individual resins can be difunctional, trifunctional, tetrafunctional or higher functionality. Useful multifunctional acrylate monomers and oligomers include:

(a) di(meth)acryl containing monomers such as 1,3-butylene glycol diacrylate, 1,4- butanediol diacrylate, 1,6-hexanediol diacrylate, 1,6-hexanediol monoacrylate monomethacrylate, ethylene glycol diacrylate, alkoxylated aliphatic diacrylate, alkoxylated cyclohexane dimethanol diacrylate, alkoxylated hexanediol diacrylate, alkoxylated neopentyl glycol diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, caprolactone modified neopentylglycol hydroxypivalate diacrylate, cyclohexanedimethanol diacrylate, diethylene glycol diacrylate, dipropylene glycol diacrylate, ethoxylated bisphenol A diacrylate, hydroxypivalaldehyde modified trimethylolpropane diacrylate, neopentyl glycol diacrylate, polyethylene glycol diacrylate, propoxylated neopentyl glycol diacrylate, tetraethylene glycol diacrylate, tricyclodecanedimethanol diacrylate, triethylene glycol diacrylate, tripropylene glycol diacrylate;

(b) tri(meth)acryl containing monomers such as glycerol triacrylate, trimethylolpropane triacrylate, ethoxylated triacrylates (e.g., ethoxylated trimethylolpropane triacrylate), propoxylated triacrylates (e.g., propoxylated glyceryl triacrylate, propoxylated trimethylolpropane triacrylate), trimethylolpropane triacrylate, tris(2-hydroxyethyl)isocyanurate triacrylate;

(c) higher functionality (meth)acryl containing monomer such as ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylate, and caprolactone modified dipentaerythritol hexaacrylate.

Oligomeric (meth)acryl monomers such as, for example, urethane acrylates may also be employed. Such (meth)acrylate monomers are widely available from Sartomer Company (Exton, PA), ALLNEX (Frankfurt am Main, Germany), and Aldrich Chemical Company (Milwaukee, WI), for example.

In some embodiments, the polyacrylate polymer includes a (meth)acrylate monomer including at least three (meth)acrylate functional groups. In some embodiments, the crosslinking monomer includes at least four, five or six (meth)acrylate functional groups. Acrylate functional groups may be favored over (meth)acrylate functional groups.

Preferred functional acrylates include, for example, trimethylolpropane triacrylate (commercially available from Sartomer under the trade designation "SR351"), ethoxylated trimethylolpropane triacrylate (commercially available from Sartomer under the trade designation "SR454"), pentaerythritol tetraacrylate, pentaerythritol triacrylate (commercially available from Sartomer under the trade designation "SR444"), dipentaerythritol pentaacrylate (commercially available from Sartomer under the trade designation "SR399"), ethoxylated pentaerythritol tetraacrylate (from Sartomer under the trade designation "SR494"), dipentaerythritol hexaacrylate, and tris(2-hydroxy ethyl) isocyanurate triacrylate (from Sartomer under the trade designation "SR368"). Aliphatic urethane acrylate oligomers may be utilized to form a preferred polyacrylate polymer to enhance compatibility of the polyacrylate polymer and the cross-linked polyurethane, although other aliphatic polyacrylate monomers may also be useful. The polyacrylates or polyurethane acrylates described herein are typically thermosetting polymers.

The polyacrylate polymer may be formed by free radical polymerization of multifunctional urethane acrylate oligomers. The urethane acrylate oligomer may be mixed with other low molecular weight monofunctional and/or multifunctional acrylates to modify the pre-cured viscosity of the resin for the purposes of processing. The average functionality of the multifunctional acrylate used in the polyurethane layer prior to cure can be less than 3 (i.e. 3 functional acrylate functional groups per molecule) or can be 2 or less. The cured (or crosslinked) material may exhibit stable material properties with respect to the display film use in application, that is, the polyurethane layer may not exhibit appreciable flow.

A urethane acrylate can be used as a shape memory and/or energy dissipating layer (e.g., any of layers 1310, 1410, 1510, or 1610 described elsewhere). In some such embodiments, the urethane acrylate can have a crosslink concentration of 0.3 to 2 mol/kg, for example. In some such embodiments, the urethane acrylate may have a glass transition temperature from -76 °C to 80 °C, from -50 °C to 50 °C, or from -20 °C to 35 °C. In some embodiments, the glass transition temperature may be greater than 30 °C, or greater than 50 °C, or greater than 80 °C (e.g., in a range of 30 °C to 100 °C). In some embodiments, the urethane acrylate layer may have a Young's modulus (e.g., at 25 °C) of at least 200 MPa, or at least 300 MPa, or at least 500 MPa, or even at least 1000 MPa (e.g., in a range of 200 MPa to 3000 MPa).

A urethane acylate can be used as a harder and/or stiffer, for example, layer at or near the nanostructured surface (e.g., any of layers 1305a, 1405a, 1405b, 1505a, 1605a, or 1605b, described elsewhere). In some such embodiments, the urethane acrylate can have a crosslink concentration of 2 to 7 mol/kg, for example. In some embodiments, the crosslink density of urethane acrylates varies from about 150 g/crosslink to about 500 grams/crosslink. In some embodiments, the average functionality of the multifunctional acrylate used prior to cure can be 2 or greater (i.e., 2 functional acrylate functional groups per molecule) or can be 3 or greater. In some such embodiments, the urethane acrylate may have a glass transition temperature of at least 50 °C, or at least 60 °C, or at least 70 °C, or even at least 80 °C (e.g., in a range of 50 °C to 120 °C). In some embodiments, the urethane acrylate layer may have a Young's modulus (e.g., at 25 °C) of at least 800 MPa, or at least 1000 MPa, or at least 1200 MPa, or even at least 2000 MPa (e.g., in a range of 800 MPa to 8000 MPa).

In some embodiments, the polyurethane has an NCO/OH ratio (also referred to as NCO/OH index) of no more than 1.06, or no more than 1.05 (e.g., in a range from 0.8 to 1.05). In some such embodiments, the polyurethane has a glass transition temperature of no more than 27 °C (e.g., in a range from 11 °C to 27 °C). The glass transition temperature can be determined by dynamic mechanical analysis (DMA), for example. The ASTM E1640-18 test standard, for example, can be used to determine the glass transition temperature by DMA. Alternatively, the glass transition temperature can be determined by differential scanning calorimetry (DSC). The ASTM D3418-15 test standard or the ASTM E1356-08(2014) test standard, for example, can be used to determine the glass transition temperature by DSC.

In some embodiments, the polyurethane is fluorinated. For example, the polyurethane may be formed using an HFPO urethane acrylate (e.g., as described further in the Examples). HFPO urethane acrylates can be incorporated into a polyurethane hardcoat are described in U.S. Pat. No. 8,147,966 (Klun et al.), for example. "HFPO-" refers to the end group F(CF(CF₃)CF₂O)_aCF(CF₃)- of the methyl ester F(CF(CF₃)CF₂O)_aCF(CF₃)C(O)OCH₃, where “a” averages 2 to 15. In some embodiments, a averages between 3 and 10 or a averages between 5 and 8. Such species generally exist as a distribution or mixture of oligomers with a range of values for a, so that the average value of a may be non-integer. In one embodiment a averages 6.2. This methyl ester has an average molecular weight of 1,211 g/mol, and can be prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.) with purification by fractional distillation. Fluorinated polyurethanes are described in U.S. Pat. Nos. 7,718,264 (Klun et al.); 8,147,966 (Klun et al.); 8,476,398 (Klun et al.); 8;729;211 (Klun et al.); and 8,981,151 (Klun et al.), for example.

A nanostructured article may include a layer (e.g., a covalently crosslinked fluorinated polymeric layer) disposed over the first nanostructures (e.g., the layer disposed over the first nanostructures of any of the embodiments of FIGS. 8-12). This layer may be a fluorinated layer and/or a low surface energy layer that improves the hydrophobicity and/or omniphobicity of the nanostructured surface of the nanostructured article. The layer may also improve the durability of the nanostructured surface.

Suitable coating materials for the low surface energy layer can include siloxane-based materials, for example plasma deposited hexamethyldisiloxane (HMDSO), or fluorinated materials like fluorinated silane coupling agents, fluorinated oligomeric materials, or plasma deposited small molecules such as those described in U.S. Pat. No. 8,158,264 (David et al.). In some embodiments, after the surface is treated with such plasma deposited materials or the surface is otherwise plasma activated, a reactive fluorochemical coating is applied over the nanostructures. Suitable fluorochemical coatings include 3M EASY CLEAN COATING ECC-1000, 3M EASY CLEAN COATING ECC-4000, 3M NOVEC 1720 ELECTRONIC GRADE COATING, and 3M NOVEC 2202 ELECTRONIC GRADE COATING, available from 3M Company (St. Paul, MN).

In some embodiments, fluorinated organosilane compounds are utilized to provide a low surface energy layer. Fluorinated organosilane compounds that are suitable are described in U.S. Pat. Appl. Pub. No. 2013/0229378 (Iyer et al.), and include those monopodal fluorinated organosilane compounds that include (a) a monovalent segment selected from polyfluoroalkyl moieties, polyfluoroether moieties, polyfluoropolyether moieties, and combinations thereof (preferably, polyfluoropolyether) and (b) a monovalent endgroup including at least one silyl moiety (preferably, one to about 20; more preferably, one to about 5; most preferably, one or two) including at least one group selected from hydrolyzable groups.

The term "hydrolysable group" in connection with the present description refers to a group which either is directly capable of undergoing condensation reactions under appropriate conditions or which is capable of hydrolyzing under appropriate conditions, thereby yielding a compound which is capable of undergoing condensation reactions. Examples of hydrolysable groups include but are not limited to hydroxyl, halogen groups, such as chlorine, bromine, iodine or fluorine, alkoxy groups (i.e. -OR'), , acyloxy groups (i.e. -O(O)CR'), amido groups (i.e. -NR' ₂), oxime groups (-O-N=CR'₂)and thiolato groups (SR'), where R' can be H, alkyl, or aryl.

As used herein, the terms "alkyl" and the prefix "alk" are inclusive of both straight chain and branched chain groups and of cyclic groups, e.g., cycloalkyl. Unless otherwise specified, these groups contain from 1 to 20 carbon atoms, in some embodiments, these groups have a total of up to 10 carbon atoms, up to 8 carbon atoms, up to 6 carbon atoms, or up to 4 carbon atoms. Cyclic groups can be monocyclic or polycyclic and preferably have from 3 to 10 ring carbon atoms.

The term “monopodal” refers to a molecule that has one silane group per molecule, with the silane group comprising at least one hydrolysable group.

The term “multipodal” refers a molecule that has more than one silane group per molecule, with each silane group comprising at least one hydrolysable group.

The term "alkylene" is the divalent form of the "alkyl" groups defined above.

Unless otherwise indicated, the term "halogen" refers to a halogen atom or one or more halogen atoms, including chlorine, bromine, iodine, and fluorine atoms.

The term "aryl" as used herein includes earbocyclic aromatic rings or ring systems optionally containing at least one heteroatom. Examples of aryl groups include phenyl, naphthyl, biphenyl, and pyridinyl.

The term "arylene" is the divalent form of the "aryl" groups defined above.

The term "carbamate" refers to the group -O-C(O)-N(R')- wherein R' is as defined above.

The term "ureylene" refers to the group -N(R')-C(O)-N(R')- wherein R' is as defined above.

The term "substituted aryl" refers to an aryl group as defined above, which is substituted by one or more substituents independently selected from the group consisting of C_1-4 alkyl, C_1-4 alkoxy, halogen, hydroxy, amino, and nitro.

The monopodal and multipodal fluorinated organosilane compounds can be used in combination. When the monovalent and/or multivalent segments of the compounds are partially fluorinated rather than perfluorinated, preferably not more than one atom of hydrogen is present for every one carbon atom, more preferably not more than one atoms of hydrogen is present per two carbon atoms, or most preferably not more than two atoms of hydrogen is present per four carbon atoms in the segment.

Suitable fluorinated organosilane compounds also include those multipodal fluorinated organosilane compounds that include (a) a multivalent (preferably, divalent) segment selected from polyfluoroalkylene, polyfluoroetheralkylene, polyfluoropolyetheralkylene, and combinations thereof (preferably, polyfluoropolyetheralkylene) and (b) at least two monovalent endgroups, each monovalent endgroup independently including at least one silyl moiety (preferably, one to about 20; more preferably, one to about 5; most preferably, one or two) including at least one group selected from hydrolyzable groups, hydroxyl, and combinations thereof.

The monovalent and/or multivalent segments are generally comprised of polyfluorocarbon, polyfluoroether, and polyfluoropolyether moieties. The monovalent and/or multivalent segments of the fluoiinated organosilane compounds are preferably perfluorinated. Preferably, the monovalent segment of the monopodal compounds include perfluoroalkyl, perfluoroetheralkyl, perfluoropolyetheralkyl, or a combination thereof (more preferably, perfluoroalkyl, perfluoropolyetheralkyl, or a combination thereof; most preferably, perfluoropolyetheralkyl), and/or the multivalent segment of the multipodal compounds includes perfluoroalkylene, perfluoroetheralkylene, perfluoropolyetheralkylene, or a combination thereof (more preferably, perfluoroalkylene, perfluoropolyetheralkylene, or a combination thereof; most preferably, perfluoropolyetheralkylene).

Useful fluorinated organosilane compounds are described in U.S. Pat. Nos. 8,158,264 (David et al.); and 9,296,918 (Olson et al.), for example. Fluorinated organosilane compounds may be described by the Formula (I) R_f[Q-(C(R)₂-Si(Y)_3-x(R^1a)_x)_y]_z, where R_f is a monovalent or multivalent segment comprised of polyfluorocarbon, polyfluoroether, and polyfluoropolyether moieties, or combinations thereof; Q is a polyvalent (e.g., an organic divalent or trivalent) linking group; each Y is independently a hydrolyzable group; R^1a is an alkyl group or aryl group; x is 0 or 1 or 2; y is 1 or 2, and z is 1, 2, 3, or 4.

For certain embodiments, including any one of the above embodiments of Formula I, the monovalent or multivalent polyfluoropolyether segment, R_f, comprises perfluorinaled repeating units selected from the group consisting of -(C_nF_2n)-, -(C_nF_2nO)-, -(CF(Z))-, -(CF(Z)O)-, -(CF(Z)C_nF_2nO)-, - (C_nF_2nCF(Z)O)-, -(CF₂CF(Z)O)-, and combinations thereof; Z is a perfluoroalkyl group, an oxygen- containing perfluoroalkyl group, a perfluoroalkoxy group, or an oxygen-substituted perfluoroalkoxy group, each of which can be linear, branched, or cyclic, and have 1 to 9 carbon atoms and up to 4 oxygen atoms when oxygen-containing or oxygen-substituted; and n is an integer from 1 to 12. Being oligomeric or polymeric in nature, these compounds exist as mixtures and are suitable for use as such. The perfluorinated repeating units may be arranged randomly, in blocks, or in an alternating sequence. For certain of these embodiments, the polyfluoropolyether segment comprises perfluorinated repeating units selected from tire group consisting of -(C_nF_2nO)-, -(CF(Z)O)-, -(CF(Z)C_nF_2nO)-, -(C_nF_2nCF(Z)O)-, -(CF₂CF(Z)O)-, and combinations thereof. For certain of these embodiments, n is an integer from 1 to 12, 1 to 6, 1 to 4, or 1 to

3.

For certain embodiments, including any one of the above embodiments, R_f is monovalent, and z is 1. For certain of these embodiments, R_f is terminated with a group selected from the group consisting of C_nF_2n+1, C_nF_2n+1O-, and X'C_nF_2nO- wherein X' is a hydrogen or chlorine atom. For certain of these embodiments, the terminal group is C_nF_2n+1- or C_nF_2n+1O)- wherein n is an integer from 1 to 6 or 1 to 3. For certain of these embodiments, the approximate average structure of R_f is C₃F₇O(CF(CF₃)CF₂O)_pCF(CF₃)- or CF₃O(C₂F₄O)_pCF₂- or wherein the average value of p is 3 to 50. In certain of these embodiments, the structure of R_f is CF₃(CF₂)_o- where o is 0-5.

For certain embodiments, including any one of the above embodiments except where R_f is monovalent, R_f is divalent, and z is 2. For certain of these embodiments, R_f is selected from the group consisting of -CF₂O(CF₂O)_m(C₂F₄O)_pCF₂-, -CF(CF₃)-(OCF₂CF(CF₃))_pO-R_f'-O(CF(CF₃)CF₂O)_pCF(CF₃)-, -CF₂O(C₂F₄O)_pCF₂-, and -(CF₂)₃O(C₄F₈O)_p(CF₂)₃-, and wherein R_f' is a divalent, perfluoroalkylene group containing at least one carbon atom and optionally interrupted in chain by O or N, m is 1 to 50, and p is 3 to 40. For certain of these embodiments, R_f' is (C_nF_2n), wherein n is 2 to 4. For certain of these embodiments, R_f is selected from the group consisting of -CF₂O(CF₂O)_m(C₂F₄O)_pCF₂-, - CF₂O(C₂F₄O)_pCF₂-, and -CF(CF₃)-(OCF₂CF(CF₃))_pO-(C_nF_2n)-O(CF(CF₃)CF₂₀)_pCF(CF₃)- and wherein n is 2 to 4, and the average value of m+p or p+p or p is from about 4 to about 24.

The above described polyfluoropolyether silanes typically include a distribution of oligomers and/or polymers, so p and m may be non-integral. The above structures are approximate average structures where the approximate average is over this distribution. These distributions may also contain perfluoropolyethers with no silane groups or more than two silane groups. Typically, distributions containing less than about 10% by weight of compounds without silane groups can be used.

The organic polyvalent (e.g., divalent or trivalent) linking group, Q, can include linear, branched, or cyclic structures, that may be saturated or unsaturated. The organic divalent or trivalent linking group, Q, optionally contains one or more heteroatoms selected from the group consisting of sulfur, oxygen, silicon, and nitrogen, and/or optionally contains one or more functional groups selected from the group consisting of esters, amides, amines, sulfonamides, carbonyl, carbonates, ureylenes, and carbamates. Q includes not less than 1 carbon atoms and not more than about 25 carbon atoms. Q is preferably substantially stable against hydrolysis. When more than one Q groups are present, the Q groups can be the same or different.

For certain embodiments, including any one of the above embodiments, Q includes organic linking groups such as -C(O)N(R)-(CH₂)_k-, -C(O)N[(CH₂)_k]₂-, -S(O)₂N(R)-(CH₂)_k-, -S(O)₂ N[(CH₂)_k]₂-, - (CH₂)_k-, -CH₂O-(CH₂)_k-, -C(O)S-(CH₂)_k-, -CH₂OC(O)N(R)-(CH₂)_k-, C(O)N(R)-(CH2)_k-OC(O)N(R)- (CH2)_k-, -C(O)N(R)-(CH₂)_k-N(R)-(CH₂)_k- and wherein R is hydrogen or C_1-4 alkyl, and k is 2 to about 25. For certain of these embodiments, k is 2 to about 15 or 2 to about 10.

In some preferred embodiments, a polyfluoropolyether silane can be utilized which has the formula R_f[Q-(C(R)₂-Si(Y)_3-x(R^1a)_x)_y]_z, where R_f is a divalent polyfluoropolyether of the formula -CF₂- (OCF₂CF₂)_m(OCF₂)_p-OCF₂-, Q = C(O)NHCH₂CH₂, R=H, Y = OCH₃, m is 1 to 50, p is 3 to 40, x = 0, y =1, and z = 2. Such polyfluoropolyether silanes are available from 3M Company under the tradenames 3M EASY CLEAN COATING ECC-1000, 3M EASY CLEAN COATING ECC-4000, or 3M NOVEC 1720 ELECTRONIC GRADE COATING, for example. A particularly useful form of this type of polyfluoropolyether silane is (CH₃O)₃Si(CH₂)₃NHCOCF₂(OCF₂CF₂)_9-10(OCF₂)_{9- 10}OCF₂CONH(CH₂)₃Si(OCH₃)₃.

In some embodiments, a perfluoroalkyl silane can be utilized which has the formula R_f[Q-(C(R)₂- Si(Y)_3-x(R^1a)_x)_y]_z, where Rf is perfluoroalkyl, Q = CH₂, R =H, Y = OCH₃, R^1a = Methyl, x = 0, y =1, and z = 1. A specific example of this type of perfluoroalkylsilane is C₄F₉CH₂CH₂Si(OCH₃)₃

In some embodiments, a perfluoroalkyl silane can be utilized which has the formula R_f[Q-(C(R)₂- Si(Y)_{3 x}(R^1a)_x)_y]_z, where R_f is perfluoroalkyl, Q = CH₂, R =H, Y = N(CH₃)₂, x = 0, y =1, and z = 1. A specific example of this type of perfluoroalkylsilane is C4F9CH₂CH₂Si(N(CH₃)₂)₃

In some preferred embodiments, a silane can be utilized which has the formula R_f[Q-(C(R)₂- Si(Y)_{3 x}(R^1a)_x)_y]_z, where R_f is perfluoroether with the formula F(CF(CF₃)CF₂O)_aCF(CF₃)-, where a averages 4-120, Q = C(O)NHCH₂CH₂, R =H, Y = OCH₃, x = 0, y =1, and z = 1. A specific example of this type of perfluoroether silane is C₃F₇O[CF(CF₃)CF₂O]₆CF(CF₃)C-(O)NHCH₂CH₂CH₂Si(OMe)₃.

In the some embodiments, a silane can be utilized which has the formula Rf[Q-(C(R)₂-Si(Y)_{3- x}(R^1a)_x)_y]_z, where Rf is perfluoroether with the formula CF_3-(CF(CF₃)CF₂O)_aCF(CF₃)- where a averages 4-120, Q = CH₂OCH₂CH₂, R =H, Y = OCH₃, x = 0, y =1, z = 1. A specific example of this type of perfluoroether silane is C₃F₇O[CF(CF₃)CF₂O]₄₀CF(CF₃)-CH₂OCH₂CH₂CH₂Si(OMe)₃.

In some preferred embodiments, a covalently crosslinked fluorinated polymeric layer is disposed on the nanostructured substrate. In some embodiments, this polymeric layer is preparable from a composition including a fluorinated silane (e.g., disilane) compound (e.g. a crosslinkable fluoropolymer with silane terminal group(s)). In some embodiments, the polymeric layer is preparable from a composition comprising a fluoropolymer comprising at least one hydrolysable terminal silane group. In some embodiments, the polymeric layer is preparable from a composition including a fluoropolymer having at least two trialkoxysilane terminal groups. In some preferred embodiments, the fluoropolymer has two trialkoxysilane terminal groups. In some embodiments, the composition is coated onto the nanostructured surface and the fluoropolymer is then crosslinked to form the covalently crosslinked fluorinated polymeric layer. In some embodiments, the fluorinated disilane compound or the fluoropolymer having at least two trialkoxysilane terminal groups is a perfluoropolyether (PFPE) amido silane compound. Such compounds are described in U.S. Pat. No. 8,158,264 (David et al.). In some embodiments, the Young's modulus (e.g., at 25 °C) of the fluorinated and/or a low surface energy layer is at least 1 MPa, or at least 5 MPa, or at least 10 MPa, or at least 50 MPa. In some embodiments, the Young's modulus (e.g., at 25 °C) of the fluorinated and/or a low surface energy layer is no more than 1000 MPa, or no more than 500 MPa, or no more than 200 MPa, or no more than 100 MPa. For example, the Young's modulus may be in a range from 1 MPa to 100 MPa, or a range of 5 MPa to 500 MPa, or in a range of 10 MPa to 200 MPa. The modulus of the fluorinated and/or a low surface energy layer can be measured by nanoindenation, for example.

In some preferred embodiments, the fluorinated and/or low surface energy layer (e.g., a covalently crosslinked fluorinated polymeric layer) has a fluorine concentration of at least 5%, or at least 15%, or at least 25%, or at least 40%, or at least 50% on an atomic basis. In some preferred embodiments, the fluorinated and/or low surface energy layer (e.g., a covalently crosslinked fluorinated polymeric layer) has a fluorine concentration of at least 10% wt, or at least 20 wt%, or at least 35 wt%, or at least 50 wt%.

In some preferred embodiments, the fluorinated and/or low surface energy layer includes a silane condensation cure catalyst. The silane condensation cure catalyst may be included to accelerate the silane hydrolysis and/or crosslinking reaction and is especially useful for substrates which should not be subjected to high temperatures. The silane condensation cure catalyst can affect the physical properties of the article, such as fluid contact angles, and resistance to abrasion. Said another way, the choice of the silane condensation cure catalyst can be tuned to the particular fluorinated silane compound in order to optimize the performance of the article, such as the resistance to abrasion. The catalyst is typically used in amounts between about 0.01 and 10wt% of the coating composition (not including solvents), more preferably between 0.05 and 5wt%, and most preferably between 0. lwt% and 5wt%.

In some embodiments, the catalyst is an acid. Suitable acid catalysts include acetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, citric acid, formic acid, triflic acid, perfluorobutylsulfonic acid, dinonylnaphthalene sulfonic acid, dinonylnaphthalene disulfonic acid, perfluorobutyric acid, p-toluenesulfonic acid, dodecylsulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid, methanesulfonic acid, sulfuric acid, hydrochloric acid, phosphoric acid, and nitric acid, for example. The catalyst can also be of a lewis acid nature, such as boron compounds such as boron trifluoride, boron tribromide, triphenylborane, triethylborane, and tris(pentafluorophenyl)borane, for example.

In some embodiments the catalyst can be a base. Examples of useful base catalysts include alkali metal hydroxides, tetraalkylammonium hydroxides, ammonia, hydoxylamine, imidazole, pyridine, N- methylimidazole, diethylhydroxylamine, and amine compounds. Especially useful are the strong neutral organic bases consisting of amidines, guanidines, phosphazenes, proazaphosphatranes, as described in US 9,175,188 B2 (Buckanin et. al).

In some embodiments, the catalyst can be organometallic compounds. Suitable catalysts include carboxylates, acetyl acetonates, and other chelates of Sn, Al, Bi, Pb, Zn, Ca, V, Fe, Ti, K, Ba, Mn, Ni, Co, Ce, and Zr, for example. Specific examples include dibutyl tin dilaurate, dibutyl tin diacetate, dibutyl tin dichloride, dibutyl tin dibromide, dibutyl tin bis(acetylacetonate), dibutyl tin dioxide, dibutyl tin dioctoate, tin (II) octoate, tin (II) neodecanoate, tetraisopropoxy titanium, tetra -n- butoxytitanium, titanium tetrakis(2 - ethylhexoxy), triethanolamine titanate chelate, titanium diisopropoxide (bis-2,4- pentanedionate), aluminum tris(acetylacetonate), aluminum titanate, zinc ethylhexanoate, K-Kat 670 (King Industries, Norwalk CT).

In some embodiments, the product of the hydrolysis reaction can be the catalyst. In some embodiments, a perfluoroalkyl silane can be utilized which has the formula Rf[Q-(C(R)₂-Si(Y)₃- _x(R^1a)_x)_y]_z, where R_f is perfluoroalkyl, Q = CH₂, R =H, Y = N(CH₃)₂, R^1a = Methyl, x = 2, y =1, and z = 1. In this case, HN(CH₃)₂ is the reaction product of the perfloroalkyl silane and water, and the HN(CH₃)₂ can serve as a condensation catalyst since it is a base.

The fluorinated compositions can be deposited using known coating methods such as dip coating or slot-die coating. In some embodiments, the fluorinated composition is vapor deposited.

If using vapor deposition, the conditions under which the fluorinated composition can be vaporized during chemical vapor deposition can vary according to the structures and molecular weights of the fluorinated compounds. For certain embodiments, the vaporizing can take place at pressures less than about 1.3 Pa (about 0.01 torr), at pressures less than about 0.013 Pa (about 10^-4 torr), or even at about 0.0013 Pa to about 0.00013 Pa (about 10^-5 torr to about 10^-6 torr). For certain of these embodiments, the vaporizing can take place at temperatures of at least about 80° C, at least about 100° C, at least about 200° C, or at least about 300°C. Vaporizing can include imparting energy by, for example, conductive heating, convective heating, and/or microwave radiation heating.

The first nanostructures may be formed on a polyurethane layer or an ionomeric or nanocomposite layer as described further elsewhere herein. The polyurethane, ionomeric or nanocomposite layer may be a (top) layer of a multilayer film. A polyurethane layer or multilayer film including a polyurethane layer can be made using known techniques. Examples of making a polymeric film include, for example, melt extrusion, melt blowing, or reacting/crosslinking monomeric species.

Film manufacturing methods are described in U.S. Pat. No. 8,765,263 (Ho et al.) and U.S. Pat. Appl. Pub. No. 2017/0107398 (Ho et al.), for example. An ionomeric or nanocomposite layer can be made by coating an aqueous dispersion onto a film and drying the coating to form the ionomeric or nanocomposite layer.

In some embodiments, a film (e.g., without a polyurethane layer) is prepared and then a polyurethane layer is applied to the film as a coating, cured and then etched to form nanostructures. The film can include at least one ionomeric or nanocomposite layer of the present disclosure.

In some embodiments, a film (e.g., without an ionomeric or nanocomposite layer) is prepared and then an aqueous dispersion described elsewhere herein layer is applied to the film as a coating, dried to form an ionomeric or nanocomposite layer and then etched to form nanostructures. In some embodiments, an aqueous dispersion of the present disclosure is coated onto a structural member (e.g., an injection molded part), dried and then etched to form nanostructures.

In some embodiments, a film including an ionomeric or nanocomposite layer and optionally a polyurethane layer (e.g., a covalently crosslinked shape memory polyurethane) is prepared and then a coating (e.g., a fluorinated polyurethane hard coat solution) is applied to the film, cured and then etched to form nanostructures.

In some embodiments, the nanostructured article includes two or more polyurethane layers. For example, the nanostructures can be formed on a first polyurethane layer that is coated onto a second polyurethane layer. The first and second polyurethane layers may have different properties (e.g., different glass transition temperatures, different crosslinking concentrations, and/or different loss tangents). In some embodiments, each of the first and second polyurethane layers may be a crosslinked polyurethane, a crosslinked polyurethane acrylate, or a crosslinked polyurethane and polyacrylate blend. The description of polyurethane layers described herein may apply to either or both of the first and second polyurethane layers in embodiments where first and second polyurethane layers are included. In embodiments, where more than two polyurethane layers are included in a nanostructured article, the description of polyurethane layers provided herein may apply to any one, or more, or all of the polyurethane layers.

FIG. 13 is a schematic cross-sectional view of a substrate 1305 that can be used to form a nanostructured article by nanostructuring the outer major surface 1304 of the first layer 1305a. The first layer 1305a is disposed on a second layer 1310. In some embodiments, the first layer 1305a is an ionomeric or nanocomposite layer described herein and the second layer 1310 is a polyurethane layer described herein. In some embodiments, the first layer 1305a includes or is formed from a first polyurethane described herein, the second layer 1310 includes or is formed from a second polyurethane described herein, and an additional layer (not shown in FIG. 13) is included (e.g., corresponding to layer 1620 of FIG. 16), where the additional layer is an ionomeric or nanocomposite layer of the present disclosure. The first and second polyurethanes may have different compositions and different mechanical properties. For example, the first polyurethane may have a higher crosslinking density and the second polyurethane may have a lower crosslinking density. The first polyurethane may have a crosslinking density in a range of 0.6 to 1.2 mol/kg or 0.65 to 1.05 mol/kg and the second polyurethane may have a crosslinking density in a range of 0.2 to 0.65 mole/kg or 0.35 to 0.65 mol/kg, for example. In some embodiments, the first layer 1305a is a covalently crosslinked polyurethane hardcoat and the second layer 1310 is a covalently crosslinked shape memory polyurethane. Useful polyurethane hardcoats are described in International Appl. Nos. US2019/012677 and IB2018/059725. In some embodiments, the first layer 1305a is a covalently crosslinked urethane acrylate and the second layer 1310 is a covalently crosslinked aliphatic polyurethane. In some embodiments, the first layer 1305a and the second layer 1310 are each covalently crosslinked shape memory polyurethanes. In some embodiments, the first layer 1305a is fluorinated.

In some embodiments, surface 1304 is nanostructured and has an overcoat layer (not shown in FIG. 13) which may be a conformal overcoat layer such as a very thin glass like coating with trimethylsilyl termination of the surface derived from plasma deposition of HMDSO, or may be a fluorosilane overcoat of a nanostructure. The layer 1305a can be an ionomeric or nanocomposite layer of the present disclosure. The layer 1310 can be any suitable substrate. The substrate may be formed of any useful polymeric material, for example, that provides desired mechanical properties (such as dimensional stability) and optical properties (such as light transmission and clarity). In some embodiments, the substrate is a polyurethane (e.g., a covalently crosslinked shaped memory polyurethane). In some embodiments, the substrate includes one or more of polyester (e.g., polyethylene terephthalate, polyethylene naphthalate), polycarbonate, polymethylmethacrylate, cyclic olefin polymer, cyclic olefin copolymer, orpolyimide. In some embodiments, the substrate is or includes a nominally colorless polyimide. Nominally colorless polyimide can be formed via chemistry or via nanoparticle incorporation. Some exemplary nominally colorless polyimides formed via chemistry are described in WO 2014/092422. Some exemplary nominally colorless polyimides formed via nanoparticle incorporation are described in Journal of Industrial and Engineering Chemistry 28 (2015) 16-27. Useful nominally colorless polyimide films may have glass transition temperatures greater 220 degrees Celsius or greater than 250 degrees Celsius or even greater than 300 degrees Celsius and tensile moduli greater than 6GPa, or greater than 6.5GPa or even Greater than 7GPa. These high modulus polymers exhibit excellent resistance to plastic deformation. In some cases, the polyimide is nominally colorless in that the b* value for the film is no more than 5. In some preferred cases, b* is no more than 4, or no more than 3, or no more than 2.

In some embodiments, surface 1304 is nanostructured and has an overcoat layer (not shown in FIG. 13) as described above. The layer 1305a can be a polyurethane acrylate (e.g., fluorinated in some cases). The layer 1310 can be an ionomeric or nanocomposite layer of the present disclosure.

FIG. 14 is a schematic cross-sectional view of a substrate 1405 that can be used to form a nanostructured article by nanostructuring the outer major surface 1404 of the first layer 1405a. The first layer 1405a is disposed on a second layer 1405b which is disposed on a third layer 1410. Layers 1405b and 1410 may be as described for layers 1305a and 1310, respectively. Layer 1405a may be a fluorinated coating (e.g., a fluorinated polyurethane) applied to layer 1405b. In some embodiments, one or two of the layers 1405a, 1405b and 1410 are polyurethane layers. In some such embodiments or in other embodiments, the layers 1405a, 1405b and 1410 have different compositions. In some embodiments, at least one of the layers 1405a, 1405b and 1410 is an ionomeric or nanocomposite layer of the present disclosure. In some embodiments, at least two of the layers 1405a, 1405b and 1410 is an ionomeric or nanocomposite layer of the present disclosure. For example, one of the layers can be an ionomeric layer (without the nanoparticles) while another of the layers can be a nanocomposite layer. In some embodiments, the first layer 1405a has a fluorine concentration of at least 2.5%, or at least 5%, or at least 10%, or even at least 20% on an atomic basis. In some embodiments, the first layer 1405a has a fluorine concentration of at least 5%, or at least 10 wt%, or at least 20 wt%, or at least 30 wt%. In some such embodiments or in other embodiments, the second and third layers 1405b and 1410 are not fluorinated or have a fluorine concentration of less than 3% on an atomic basis. In some embodiments, the first layer 1405a is a fluorinated polyurethane hardcoat.

In some embodiments, surface 1404 is nanostructured and has an overcoat layer (not shown in FIG. 14) as described above for surface 1304. In some embodiments, the layer 1405a is an ionomeric or nanocomposite layer of the present description and layer 1405b is a different ionomeric or nanocomposite layer of the present description. For example, the ionomeric or nanocomposite used in layer 1405b may be selected to provide improved adhesion between layers 1405a and 1410, while the ionomeric or nanocomposite used in layer 1405a may be selected for durability or other mechanical properties, for example. The layer 1410 can be any of the substrates described for layer 1310, for example. In some embodiments, surface 1404 is nanostructured and has an overcoat layer (not shown in FIG. 14) as described above for surface 1304. In some embodiments, the layer 1405a is a polyurethane acrylate layer, which can optionally be fluorinated. In some embodiments, the layer 1405b is a different polyurethane acrylate layer, which is typically not fluorinated. The layer 1410 can be ionomeric or nanocomposite layer of the present disclosure. In some embodiments, layer 1410 is replaced with a substrate that includes at least one ionomeric or nanocomposite layer. For example, the substrate can include an ionomeric layer and a nanocomposite layer.

Additional layers can optionally be included between the first and second layers 1305a and 1310 or between the second and third layers 1405b and 1410.

FIG. 15 is a schematic cross-sectional view of a substrate 1505 including first and second layers 1505a and 1507. In the illustrated embodiment, the substrate 1505 further includes an optional third layer 1510. A plurality of first nanostructures may be integrally formed with at least the first layer 1505a as described further elsewhere herein. The layers 1505a and 1510 may correspond to the layers 1305a and 1310 described elsewhere. In some embodiments, the second layer 1507 is electrically conductive. In some embodiments, the second layer 1507 has a sheet resistance of less than 10¹⁰ ohms/sq, or less than 10⁶ ohms/sq, or less than 1000 ohms/sq, or less than 100 ohms/sq. In some embodiments, the second layer 1507 has a sheet resistance in range of 50 ohms/sq to 1000 ohms/sq or to 10⁶ ohms/sq or to 10⁸ ohms/sq. In some embodiments, the second layer 1507 is a substantially transparent antistatic layer. In some embodiments, the second layer 1507 has an antistatic property such that a nanostructured article formed on the substrate 1505 has a charge decay time of less than 10 seconds, or less than 5 seconds or less than 2 seconds, less than 1 second, or even less than 0.5 seconds. The charge decay time can be determined according to the MIL-STD 3010, Method 4046, formerly known as the Federal Test Method Standard 10113, Method 4046, "Antistatic Properties of Materials", for example.

Articles, such as optical articles that typically are composed of electrically insulating materials, may tend to get charged with static electricity. The charges which are present at the surface of the article creates an electrostatic field capable of attracting and fixing small particles (e.g., dust and/or water droplets) moving near the charged surface. An antistatic layer (also referred to as an antistat layer) can be included in the article to induce a high mobility of the charges. This can decrease the number of static charges which are present at the surface of the article which would decrease the intensity of the electrostatic field, thereby decreasing attraction of the particles to the surface.

“Antistatic” generally refers to the property of not retaining and/or developing an appreciable electrostatic charge. An article may be considered to have desired antistatic properties when it does not attract or fix dust or small particles after one of its surfaces has been rubbed with an appropriate cloth.

The ability of an article to evacuate a static charge can be quantified by measuring the time for the charge to dissipate (charge decay time). Antistatic optical articles may have a discharge time of less than 1 second (e.g., the discharge time may be on the order of 100-200 milliseconds), while static optical articles have a discharge time on the order of several tens seconds, sometimes even several minutes. A static article having just been rubbed can thus attract surrounding dust particles, for example, until the discharge time has passed.

The charge decay time can be determined using the following method. Sheets of test materials can be cut into 12 cm by 15 cm samples and conditioned at relative humidity (RH) of about 50% for at least 12 hours. The materials can be tested at temperatures that ranged from 22 to 25°C. The static charge dissipation time can be measured according to MIL-STD 3010, Method 4046, using an ETS Model 406D Static Decay Test Unit (manufactured by Electro-Tech Systems, Inc.). This apparatus induces an initial static charge (Average Induced Electrostatic Charge) on the surface of the flat test material by using high voltage (5000 volts), and a field meter allows observation of the decay time of the surface voltage from 5000 volts (or whatever the induced electrostatic charge was) to 10 percent of the initial induced charge. This is the static charge dissipation time. The lower the static charge dissipation time, the better the antistatic properties are of the test material.

Transparent antistatic coatings may be obtained by vapor deposition of metals or metal -oxides like indium tin oxide or vanadium oxide. Other transparent conductive layers can also be used to provide antistatic properties. Coated Silver nanowire coatings and patterned nanowire coatings can be used. Patterned metal mesh coatings may be used as well. Patterned conductive coating may also have the benefit of being used for resistive heating elements in addition to having antistatic properties.

Antistatic coatings may be applied by wet route, i.e., by applying a flowable composition that is subsequently cured. Antistatic properties in such coatings are typically obtained by incorporation of specific additives into an aqueous based composition (e.g., a hard coating composition). Conductive polymers, for example, may be used as the additives in wet coatings. These polymers can build a percolating network allowing for charge dissipation. A useful transparent conductive polymer is poly(3,4- ethylenedioxythiophene) (PEDOT) which can be modified to be added in aqueous compositions, which can be desirable for environmental and health reasons. For example, PEDOT can be grafted with Poly Styrene Sulfonate (PSS), allowing for good dispersion in water. To further enhance conductivity, various additives may be used such as sulfonate surfactant as described in U.S. Pat. Appl. Pub. No. 2011/0248223 (Zheng), for example. Other conductive additives like carbon nanotubes can also be used.

Another method to provide electrical conductivity in aqueous based compositions is to incorporate very light charge holders, such as positively charged lithium cations, in the composition.

Another approach to proving a substantially transparent electrically conductive layer is to include an ionic liquid in a polymeric layer as described in JP Pat. Appl. Pub. No. 2008/184556, for example.

Another approach to proving a substantially transparent electrically conductive layer is to include a polymerizable onium salt as described in U.S. Pat. Appl. Pub. Nos. 2012/0225301 (Hunt et al.) or 2012/0288675 (Klun et.al.), for example.

The nanostructure article may optionally include other layers. The substrate may be or include a multilayer film. In some embodiments, the multilayer film includes at least a polyurethane layer and an adhesive layer. In some such embodiments, the adhesive layer may bond the nanostructured article to an exterior surface. In some embodiments, the multilayer film includes layers corresponding to layers 1405a and 1405b and/or includes a layer corresponding to the layer 1507 and/or includes an additional polymeric layer.

In some embodiments, the outer surface of layer 1505a is nanostructured and has an overcoat layer (not shown in FIG. 15) as described for above for some embodiments of surface 1304. In some embodiments, the layer 1405a is an ionomeric or nanocomposite layer of the present description. The layer 1507 is an antistat layer as described elsewhere. The layer 1410 can be any of the substrates described for layer 1310, for example.

In some embodiments, the outer surface of layer 1505a is nanostructured and has an overcoat layer (not shown in FIG. 15) as described for some embodiments of surface 1304. In some embodiments, the layer 1505a is a polyurethane acrylate layer, which can optionally be fluorinated. The layer 1507 is an antistat layer as described elsewhere. The layer 1410 can be an ionomeric or nanocomposite layer of the present disclosure. In some embodiments, layer 1410 is replaced with a substrate that includes at least one ionomeric or nanocomposite layer. For example, the substrate can include an ionomeric layer and a nanocomposite layer.

FIG. 16 is a schematic cross-sectional view of a nanostructured article 1600 including a plurality of nanostructures 1603 disposed on a multilayer film substrate. A contact angle Q (e.g., advancing, static, or receding) of a droplet 1667 (e.g., a water or hexadecane droplet) with the nanostructured surface is schematically illustrated. The nanostructures 1603 may correspond to first or second nanostructures described elsewhere herein. The nanostructured article 1600 may be a flexible film. The substrate may be regarded as the stack of layers underthe nanostructures 1603, or the layer 1605a and optionally one or more additional layers under the layer 1605a may be regarded as the substrate and the remaining layers may be regarded as additional layers disposed on the substrate. The layers 1605a and 1605b may correspond to layers 1405a and 1405b described elsewhere. In other embodiments, the layers 1605a and 1605b may be replaced by a single layer which may, for example, correspond to layer 1305a described elsewhere. The layer 1607, which may be omitted in some embodiments, may correspond to layer 1507 and may be a substantially transparent antistatic layer, for example. The layer 1610 may correspond to any of layers 1310, 1410 or 1510, for example, and may be a polyurethane layer or an ionomeric or nanocomposite layer as described elsewhere herein. Any of the layers 1310, 1410, 1510, or 1610 may be one or more of a covalently crosslinked aliphatic urethane layer, a covalently crosslinked urethane acrylate layer, a covalently crosslinked shape memory layer, an ionomeric layer, a nanocomposite layer, or an energy dissipation layer.

In some embodiments, layer 1605a is a fluorinated polyurethane layer, layer 1605b is an ionomeric or nanocomposite layer, and layer 1610 is a polyurethane layer. In some embodiments, layer 1605a is a fluorinated polyurethane layer, layer 1605b is a polyurethane layer, and layer 1610 is an ionomeric or nanocomposite layer. In some embodiments, layers 1605a and 1605b are replaced with a single nanocomposite layer and layer 1610 is a polyurethane layer or an ionomeric layer or a nanocomposite layer. Layers 1605a, 1605b and 1610 can be as described elsewhere for any embodiments of layers 1405a, 1405b, and 1410, for example.

The thickness of the layers 1605a or 1605b or a combined thickness of the layers 1605a and 1605b may be in a range of 1 to 50 micrometers, or 2 to 20 micrometers, or 3 to 13 micrometers, for example. The thickness of the layers 1610 or 1620 or a combined thickness of the layers 1610 and 1620 may be in a range of 50 to 500 micrometers, or to 200 micrometers, or to 150 micrometers, or to 100 micrometers, for example. The thickness of the layer 1607 may be in a range of 50 nm to 1 micrometer, or 80 nm to 500 nm, or 80 nm to 200 nm, for example.

The layer 1620 may have a yield stress value greater than 70 MPa, or greater than 90 MPa, or greater than 120 MPa, or greater than 160 MPa. The yield stress in this context refers to the 0.2% offset yield stress and can be determined according to the ASTM D638-14 test standard, for example. The layer 1620 may be formed of any useful polymeric material that provides the desired mechanical properties (such as dimensional stability) and optical properties (such as light transmission and clarity). Examples of materials suitable for use in the layer 1620 include polymethylmethacrylate, polycarbonate, polyamides, polyimide, polyesters (e.g., polyethylene terephthalate (PET), polyethylene naphthalate (PEN)), polycyclic olefin polymers, and thermoplastic polyurethanes. One useful polymeric material for forming the layer 1620 is polyimide. In some embodiments the polyimide substrate layer is colorless or substantially colorless. Colorless polyimide can be formed via chemistry or via nanoparticle incorporation. Some exemplary colorless polyimides formed via chemistry are described in U.S. Pat.

Appl. Pub. No. 2015/0322223 (Woo et al.), for example. In some cases, the layer 1620 may include a multilayer optical film construction which has desired optical functions or properties. For example, the optical film may include a wavelength selective filter. In cases where transparency over the visible range is not desired, the layer 1620 may be or include a colored film that may be partially transparent or non- transparent film. For example, the film may be a white or colored film.

The layer 1620 may be primed or treated to impart some desired property to one or more of its surfaces. For example, the layer 1620 can be primed to improve adhesion to the layer 1620 or to the layer 1640 which may bean optically clear adhesive layer. Examples of such treatments include corona, flame, plasma and chemical treatments such as, acrylate or silane treatments.

The layer 1640, which may be omitted in some embodiments, may be an adhesive layer which may be one or more of an optical adhesive layer, a pressure sensitive adhesive layer, or a hot melt adhesive layer. The adhesive may be formed of acrylate, silicone, silicone polyoxamide, silicone polyurea, polyolefin, polyester, polyurethane or polyisobutylene. In some cases, the adhesive layer used in conjunction with a sensor assembly, or with a surface to be protected, may be a self-wetting layer adapted to wet out to the surface to which it is attached. In some cases, the nanostructured article may be attached to a surface using a liquid adhesive layer that may or may not cure following application.

Release liners may be disposed on the outer major adhesive surface of any nanostructured article including an adhesive layer. The release liners may also be referred to as premask layers that may be easily removed for application to a surface.

In some embodiments, the adhesive layer may have high transmittance and low haze with respect to one or more specific wavelengths of electromagnetic radiation, e.g. visible radiation (visible light), infrared radiation, ultraviolet radiation, sound and radio waves. In some embodiments, the adhesive layer may be wavelength selective (e.g., the adhesive layer may include dyes and/or pigments).

In some embodiments, the transmittance of the nanostructured article 1600 to one or more radiation wavelengths may be at least 80%, at least 85%, at least 90%, or at least 92%. For example, in some embodiments, the transmittance of the nanostructured article 1600 with respect to visible light (average optical transmittance) may be in any of these ranges. In some embodiments, it is a benefit to have the nanostructured article 1600 to maintain a haze measurement of less than 5%, less than 3%, less than 2%, or even less than 1% with respect to one or more specific wavelengths of electromagnetic radiation. In some embodiments, the haze of the nanostructured article 1600 with respect to visible light (optical haze) may be less than 5%, less than 3%, less than 2%, or even less than 1%. In some embodiments, it is a benefit to have the nanostructured article 1600 to maintain a clarity measurement of at least 95%, at least 98%, or at least 99% with respect to one or more specific wavelengths of electromagnetic radiation. In some embodiments, the clarity of the nanostructured article 1600 with respect to visible light (optical clarity) may be at least 95%, at least 98%, or at least 99%. In some embodiments, the average optical transmittance, optical haze and/or optical clarity is in any of these ranges after the nanostructured surface of the nanostructured article 1600 has been abraded for 10 cycles at a rate of 60 cycles/min with an AATCC (American Association of Textile Chemists and Colorists) Crockmeter Standard Rubbing Cloth using a 1-inch diameter circular abrading head and a 350 g force, as described further in the Examples. The nanostructured surface may have contact angles (advancing or receding, for water or for hexadecane) in any of the ranges described elsewhere herein, and/or water roll- off angles in any of the ranges described elsewhere herein, before and after it has been abraded.

In some cases, an optional additional border print material 1630 may be included. In the illustrated embodiment, the border print material 1630 is disposed between the layers 1620 and 1640. For example, the border print material 1630 may be printed onto layer 1620 before adhesive layer 1640 is applied. In other embodiments, the layer 1620 may be omitted and the border print material 1630 may be printed onto layer 1610.

The nanostructured article 1600 may include additional substrate layers such as those described, for example, in U.S. Pat. Appl. Pub. No. 2017/0107398 (Ho et al.).

In some embodiments, the nanostructured article 1600 includes an additional layer that includes printing (e.g., ink printing) and/or a graphic, for example.

In some embodiments, a nanostructured article includes a first layer and a plurality of first nanostructures integrally formed with the first layer. The first layer can be a polyurethane layer or an ionomeric or nanocomposite layer. For example, any of layers 1310, 1410, 1510, or 1610 may be a polyurethane layer or an ionomeric or nanocomposite layer which can be taken to be the first layer and the first nanostructures may be integrally formed with the first layer by applying one or more coatings to the first layer (e.g., each of layers 1605a, 1605b, and 1607 may be applied to layer 1610 as a coating), drying and/or curing the coating(s), and then etching nanostructures into the outer coating layer as described further elsewhere herein. The outer coating layer may be an ionomeric or nanocomposite layer formed by coating and drying an aqueous dispersion as described further elsewhere herein. In some embodiments, a substrate includes the first layer and a second layer, and optionally additional layers, where the first and second layers are independently selected from the group consisting of polyurethane layers, ionomeric layers, and nanocomposite layers. In some preferred embodiments, at least one layer of the substrate is an ionomeric or nanocomposite layer. In embodiments where the first or second layer is a polyurethane layer, the polyurethane layer preferably includes covalently crosslinked polyurethane having a crosslink concentration in a range from 0.3 to 1.05 mol/kg, or in a range of 0.3 to 0.65. In some embodiments, the covalently crosslinked polyurethane has a peak tan δ greater than 1, or greater than 1.2, or greater than 1.3, or greater than 1.4, or greater than 1.5.

In some embodiments, the plurality of first nanostructures extend away from the first layer (e.g., the polyurethane layer or the ionomeric or nanocomposite layer) along a length of the first nanostructures, the plurality of first nanostructures having an average length L1 and an average width W1, W1 being in a range of 5 nm to 500 nm, L1/W1 being at least 1. W1, L1, and L1/W1 may be in any of the ranges described elsewhere herein. A fluorinated and/or low surface energy layer (e.g., a covalently crosslinked fluorinated polymeric layer) may be disposed over the first nanostructures as described further elsewhere herein (e.g., corresponding to layer 801 of FIG. 8 or to a corresponding layer of other figures described elsewhere).

In some embodiments, the nanostructured article is one or more of a polymeric film, a protective film, a multilayer film, or a flexible film. For example, in some embodiments, the nanostructured article is a flexible film than can be bent 180 degrees around a cylindrical mandrel having a diameter of 10 cm, or 3 cm, or 1 cm, or 5 mm, or 3 mm, or even 1 mm without breaking or cracking. The films described herein can be added (e.g., bonded) to a surface to be protected using methods known in the art. For example, a premask may be used to assist in the application process. Specifically, applying the film to a substrate (e.g. an exterior surface of a vehicle sensor system) using a layer of premask material including a polymeric cover sheet or layer and a layer of removable pressure-sensitive adhesive firmly adhered to one surface of the cover sheet with the layer of premask material, where the premask is removed after placement. Additionally, the film may be die-cut to match a desired surface to be protected.

FIGS. 17A-17B schematically illustrate applying a first nanostructured article 1700 to a member 1750 (e.g., a structural member) having a surface 1751 that is to be protected by the first nanostructured article 1700 to form a second nanostructured article 1799. First nanostructured article 1700, which may be a flexible film, includes a nanostructured substrate 1705 disposed on an adhesive layer 1740 (FIG. 17A). Second nanostructured article 1799 includes the first nanostructured article 1700 bonded to the member 1750 (FIG. 17B). The surface 1751 may be planar or non-planar (e.g., curved).

In some embodiments, the nanostructured article is disposed on, and integrally formed with, a structural member. As used herein, a first element “integrally formed” with a second element means that the first and second elements are manufactured together rather than manufactured separately and then subsequently joined. Integrally formed includes manufacturing the second element followed by manufacturing the first element on the second element. For example, a structural member may be manufactured by injection molding and then the nanostructured article may be manufactured on the structural member by coating an exterior surface of the structural member with an aqueous dispersion of the present disclosure, drying the dispersion to form an ionomeric or nanocomposite layer, etching nanostructures into the ionomeric or nanocomposite layer (e.g., by adding an etch mask to an ionomeric layer or by using the nanoparticles of a nanocomposite layer as an etch mask), and optionally coating the nanostructures with a layer that is subsequently cured to form a covalently crosslinked fluorinated polymeric layer. In other embodiments, a structural member may be manufactured by injection molding and then the nanostructured article may be manufactured on the structural member by coating an exterior surface of the structural member with a polyurethane solution, for example, curing the polyurethane, etching nanostructures into the cured polyurethane, and optionally coating the nanostructures with a layer that is subsequently cured to form a covalently crosslinked fluorinated polymeric layer. Prior to coating with the polyurethane solution, the structural member can be coated with an aqueous dispersion of the present disclosure, which is dried prior to applying the polyurethane solution, so that the resulting nanostructures are formed in a polyurethane layer disposed one an ionomer or nanocomposite layer described herein.

A structural member is a member or element capable of substantially maintaining its shape when subject to external forces. A structural member may be, for example, one or more of an injection molded part, a housing for an electronic device, a housing of a lighting assembly such as an automotive headlight or taillight housing, an optical lens, a device cover, a window (e.g., an architectural widow or automobile window (e.g., an automobile windshield)), a windshield, a mirror, and a mirror housing assembly (e.g., automotive sideview mirror housing assembly).

FIGS. 18A-18C schematically illustrate integrally forming a nanostructured article with a structural member. A structural member 1850 is provided (FIG. 18A). Structural member 1850 may be made by injection molding, for example. A coating 1805 (e.g., an aqueous dispersion described elsewhere herein) is applied to a surface 1851 of structural member 1850 that is to be protected (FIG. 18B). The coating 1805 is then dried and etched (and optionally coated with a fluorinated and/or low surface energy layer) as described elsewhere herein to form a first nanostructured article 1800 disposed on, and integrally formed with, structural member 1850 (FIG. 18C). A second nanostructured article 1899 includes the first nanostructured article 1800 and the structural member 1850. The surface 1851 may be planar or non- planar (e.g., curved). The nanostructured article (e.g., 1700 or 1800) may be disposed on any surface where a hydrophobic surface is desired to reduce water droplet build up, for example. Example applications include detectable markers, signs or logos, emblems, windows, windshields, mirrors (e.g., side mirrors, rear view mirror, bathroom mirror), eyeglasses, surfaces of optical systems (e.g., virtual or augmented reality systems), and light sources such as search lights or beacons, airport runway lighting, street lighting, traffic lights, exterior or interior lighting, and exterior surface of a sensor system, for example.

A detectable marker may be a road sign, for example. A nanostructured surface may be disposed on the road sign to protect the sign from build-up of snow or ice, for example. In some embodiments, a road sign is provided that includes a retroreflective article and a nanostructured article described elsewhere disposed on the retroreflective article. Retroreflectors are described in U.S. Pat. Appl. Publ. No. 2008/0212181 and 2004/0174601 (Smith), for example, and in U.S. Pat. Nos. 5,417,515 (Hachey et al.); and 6,677,028 (Lasch et al.), for example.

In some embodiments, member 1750 or member 1850 is a housing (e.g., a device enclosure). For example, member 1750 or 1850 may be hollow such that an electronic device can be housed within the member. In some embodiments, member 1750 or member 1850 is a device cover. For example, member 1750 or 1850 may be solid cover layers for an electronic device (e.g., a cover disposed over a sensor). In some embodiments, the nanostructured article 1799 or 1899 is a housing or a device cover.

FIG. 19 is a schematic cross-sectional view of a system 1970 including a nanostructured article 1999 and an electronic device 1960 disposed proximate the nanostructured article 1999. In the illustrated embodiment, the nanostructured article 1999 has a curved, nanostructured surface 1907. The nanostructured article 1999 may be an optical lens, for example. In other embodiments, the nanostructured article 1999 may have a different shape depending on its intended use.

The electronic device 1960 may be configured to emit or receive energy (e.g., electromagnetic energy (e.g., ultraviolet, visible, infrared, or millimeter wave) or acoustic energy (e.g., ultrasonic, sonic, or subsonic)). In some embodiments, the electronic device 1960 is or includes one or more of an electromagnetic radiation emitter, an electromagnetic radiation sensor, an acoustic emitter, and an acoustic sensor. In some embodiments, the electronic device 1960 is or includes one more of a camera, a LIDAR (light detection and ranging) unit, a radar unit, a sonar unit, and a 5G antenna system. The camera can be any suitable type of camera for a given application and may detect wavelengths in any suitable range (e.g., ultraviolet, visible, and/or infrared).

In some embodiments, a system includes a nanostructured article anywhere in the system in the path (e.g., optical or acoustical path) from an energy emitter to a target to a sensor. In other words, the nanostructured article can be disposed on any intervening element along the energy's round-trip journey from source to object to detector. For example, in some embodiments, the system includes an electronic device which may include an emitter having a light source including a focusing optic and/or a module cover over the light source and which may include a camera having a camera housing or camera lens covering a camera sensor. In some such embodiments, the system includes a nanostructured article described herein disposed on any one or more of a focusing optic, a module cover, a windshield (e.g., if optical or acoustic energy is transmitted through the windshield), a bumper (e.g., if optical or acoustic energy is transmitted through the bumper), a retroreflective material (e.g., in a road sign), a camera housing, or a camera lens.

In some embodiments, the nanostructured article 1999 and the electronic device 1960 are proximate to, and spaced apart from, one another. For example, the nanostructured article 1999 may be disposed in one area of an automobile while the electronic device is disposed in another area of the automobile. In some such embodiments or in other embodiments, the nanostructured article 1999 is disposed such that electromagnetic or acoustic energy passes through the nanostructured article to and/or from the electronic device 1960. In some embodiments, an element or body is disposed between the nanostructured article 1999 and the electronic device 1960. In some embodiments, the nanostructured article 1999 is a housing and the electronic device 1960 is disposed in the housing. In some embodiments, the nanostructured article 1999 includes the electronic device 1960 within a housing having the nanostructured surface 1907. Similarly, in some embodiments, an electronic device is disposed within structural member 1750 or 1850. In some such embodiments, the nanostructured article (1999, 1899, or 1799) is one or more of a sensor, a camera, a LIDAR unit, a radar unit, and a sonar unit.

In some embodiments, the nanostructured article is an optical lens. The nanostructures may be disposed on a curved surface of the lens as schematically illustrated in FIG. 19, for example. Alternatively, an optical lens may have a plurality of planar facets and a nanostructure may be disposed on the facets. Faceted lenses are described in US 2017/0122524 (Wu et al.), for example.

In some embodiments, the nanostructured article includes more than one nanostructured surface. For example, the nanostructured article may be a vehicle sensor that includes an exterior surface of a housing and a lens disposed in the housing where both the exterior surface and the lens surface are nanostructured as described herein. As another example, in the case of a transparent housing element, the inside and outside surface of the transparent housing may both be nanostructured.

The nanostructured article may have a spatially variant nanostructure geometry. For example, one facet of a faceted lens may have a nanostructured surface as schematically depicted in any one of FIGS. 1-12 and a different facet may have a nanostructured surface as schematically depicted in any different one of FIGS. 1-12. As another example, the nanostructured surface may include holes or microchannels (regions without nanostructures) which may aid in water runoff, for example. In some embodiments, the nanostructures may have a variable directionality. For example, the nanostructures may be posts (e.g., nano-pillars or nano-columns) that extend generally normal to a curved surface. In other embodiments, the nanostructures may extend generally along a same direction that is not normal to at least portions of the curved surface. The direction that the nanostructures extend can be controlled by the etching technique used to make the nanostructures (e.g., in embodiments where the nanostructures are formed by reactive ion etching, the direction of the nanostructures can be controlled by controlling the direction of the ion beam). In some embodiments, the nanostructured surface of the nanostructured article is patterned such that some regions of the surface include the nanostructures and other regions do not. This may be desired, for example, in some embodiments where is it is desired for nanostructured surface to be (super)hydrophobic or (super)omniphobic in a plurality of discrete regions (e.g., spaced apart regions covering different sensor apertures) and to provide other protection (e.g., abrasion resistance) between the discrete regions. Regions including the nanostructures may have the contact angles, average optical transmittance, optical haze, and/or optical clarity described elsewhere herein.

In some embodiments, the nanostructured article is used in a vehicle. The use of sensor technology in vehicles has increased. For example, autonomous and semi-autonomous vehicles have the potential to be used in an increasing number of applications. Such autonomous vehicles include at least one vehicle sensor system configured to receive information regarding, for example, the surrounding terrain, upcoming obstacles, a particular path, etc. In some instances, the vehicle sensor system is configured to automatically respond to this information in place of a human operator by commanding a series of maneuvers so that the vehicle is able to negotiate the terrain, avoid the obstacles, or track a particular path with little or no human intervention. Examples of various types of sensors used to detect objects in the surroundings may include lasers or LIDAR, sonar, ultrasonic sensors, radar, cameras, and other devices which have the ability to scan and record data from the vehicle's surroundings. Such scans are initiated or received through an exterior facing element. The exterior facing element may be part of the scanning sensor itself or may be an additional part of the vehicle sensor system that shields or protects more fragile parts. Examples of such exterior facing elements include a windshield (if a sensor is placed behind the windshield), a headlight (if sensor is placed behind the headlight), a protective housing and the surface of a camera lens. The exterior facing element has a surface (the exterior surface) which is exposed to elements, for example temperature, water, other weather, dirt and debris. Any of these elements can interfere with the exterior facing element, and can compromise the scan going out or the data coming in to the vehicle sensor system. A nanostructured article of the present description can be disposed on the exterior surface to protect the surface from the build-up of water, ice, dirt and/or debris, for example.

FIGS. 20-21 schematically illustrate possible surfaces where a nanostructure of the present description can be advantageously utilized.

FIG. 20 is a schematic front perspective view of an automobile 2090 including a rear-view mirror assembly 2091, side view mirror assemblies 2092, a rear quarter panel 2093, front bumper 2096, headlight assembly 2097, and windshield 2098.

FIG. 21 is a schematic rear view of an automobile 2190 including side view mirrors 2182, rear bumper 2186, taillight assembly 2188, and backup camera 2189.

In some embodiments, a sensor system (e.g., including a sensor and an emitter) is included in the headlight assembly 2097 and/or taillight assembly 2188 and a nanostructured surface described herein is disposed on at least a portion of the outer surface of the lighting assembly (2097 and/or 2188) covering the sensor system. In some embodiments, the nanostructured surface covers at least a majority (e.g., all or substantially all) of the outer surface of the lighting assembly. In some embodiments, a nanostructured surface is provided on a lens or cover glass of the sensor system.

In some embodiments, a sensor system is incorporated in the rear-view mirror assembly 2091. At least a portion of the windshield 2098 that is disposed in front of the rear- view mirror assembly 2091 may include a nanostructured surface described herein to prevent elements (e.g., water or ice) from building up on the windshield 2098 that could interfere with the functioning of the sensor system.

In some embodiments, a sensor system, such as a LIDAR system, a radar system, or a sonar system, is disposed under hood location 2095, or in a roof location 2094, or within front bumper 2096 or rear bumper 2186, or within side view mirror assemblies 2092, or under rear quarter panel 2093. In some embodiments, the sensor system includes a nanostructured surface described herein on a cover or lens of the sensor system. In some embodiments, the exterior vehicle surface includes a nanostructured surface described herein. For example, any one or more of the front bumper 2096, the rear bumper 2186, the side view mirror assemblies 2092, or the rear quarter panel 2093 may include a nanostructured surface described herein. In some embodiments, a nanostructured article is integrally formed with any one or more of the front bumper 2096, the rear bumper 2186, the side view mirror assemblies 2092, or the rear quarter panel 2093. In some embodiments, a nanostructured article is a flexible film bonded to any one or more of the front bumper 2096, the rear bumper 2186, the side view mirror assemblies 2092, or the rear quarter panel 2093. In some embodiments, a nanostructured surface described here is applied (e.g., integrally formed with or applied as a film) to the side-view mirrors 2182 or an outer lens of the backup camera 2189, for example.

In some embodiments, the nanostructured article is a sensor (e.g., backup camera 2189), a window (e.g., windshield 2098), a lighting assembly (e.g., headlight assembly 2097 or taillight assembly 2188), a mirror (e.g., side view mirror 2182), an automotive side-view mirror assembly (e.g., side-view mirror assembly 2092), or a vehicle body panel (e.g., quarter panel 2093, or bumper 2186 or 2096).

Examples

Table 1: List of Materials used.

Preparatory Examples

Preparation of HFPO-UA

A 500mL round bottom flask equipped with magnetic stirbar was charge with 25.0g (0.131 equivalents, 191 equivalent weight) DESMODURNIOO, and 128.43 g MEK. The reaction mixture was swirled to dissolve all of the reactants and the flask was placed in an oil bath at 55°C and was fitted with an adapter under dry air. Next, 0.10g of a 10% by weight solids solution in MEK of dibutyltin dilaurate was added to the reaction. Via an addition funnel, 17.50g (0.0131 equivalents, 1344 equivalent weight) of HFPO-C(O)N(H)CHCH-OH was added to the reaction over about 20 min. (The HFPO alcohol (HFPO-C(O)N(H)CHCH-OH) can be made by a similar procedure to that described in U.S. Pat. Pub. No. 2004/0077775 A1 (Audenaert et al.), titled “Fluorochemical Composition Comprising a Fluorinated Polymer and Treatment of a Fibrous Substrate Therewith”. The HFPO alcohol was made using an HFPO methyl ester F(CF(CF3)CF2))aCF(CF3)C(O)OCH3 where a = 6.67. The HFPO methyl ester can be prepared according to the method reported in U.S. Pat. No. 3,250,808 (Moore et al.).) The addition funnel was rinsed with ~15g of MEK. Two hours after the addition was complete, 0.52g of BHT was added directly into the reaction, followed by dispensing 61.46g (0.1243 equivalents, 494.3 equivalent weight) of Sartomer SR444c from a beaker. The beaker was rinsed with ~30g of MEK. The reaction was monitored by Fourier-transform infrared spectroscopy (FTIR) for the disappearance of -NCO. The reaction was deemed complete when the FTIR spectrum showed no peak due to an -NCO functional group at ~2265cm-1 after 20h of additional reaction. The reaction flask and contents were weighed, and the reaction was then adjusted to 30% solids by addition of 2.23g of MEK to provide a clear light yellow solution.

Preparation of DBU catalyst solution

EtOH was dried over 3 A Mol Sieves before use. In a 25 mL glass vial, 1.0 g of DBU was added, followed by 18.5 g EtOH and then 0.5g HOAc. The solution was mixed for 10 s using a vortex mixer (Cole Parmer, Vernon Hills, IL).

Preparation of 85/15 TFT/EtOH Solution

EtOH was dried over 3A Mol Sieves before use. In a 250 mL glass jar, 85 g of TFT was added, followed by 15 g EtOH and swirled to mix.

Preparation of POS-1 Polymerizable Onium Salt

Polymerizable Onium Salt 1, (Acryloyloxyethyl)-N,N,N-trimethylammonium bis(trifluoromethanesulfonyl)imide, was prepared as described in PCT Pub. No. WO 2011/02596320 A1 (Hunt et al.) Examples, page 19 line 24, Polymerizable Onium Salt 1 (POS-1).

Preparatory Example 1: preparation of carboxylic acid silane solution

2500 grams of DMF was placed in a 4 liter brown glass jug. A Teflon coated stir bar was added to the jug, the jug was placed on a stir plate, and stirring initiated. 225 grams of succinic anhydride (SA) was added to the jug which dissolved in the DMF. 400 grams of 3 aminopropyltrimethoxysilane (APTMS) was slowly added to the jug. The solution in the jug was continuously stirred for 24 hours at room temperature to complete synthesis of the carboxylic acid silane which was confirmed by NMR. The resulting solution had 20.0 % by weight carboxylic acid silane in DMF. The carboxylic acid silane reaction is believed to be as follows:

Preparatory Example 2: Carboxylic acid modified SiO₂ nanodispersion

49.33 kilograms of aqueous colloidal silica dispersion (NALCO 2327) was placed in a 75.71 liter stainless steel reactor. Agitation was initiated. 15.58 kilograms of carboxylic acid silane solution (Preparation Example 1) was added to the reactor. The contents of the reactor were heated to 80°C.

Upon reaching 80°C, the reactor was sealed, and the contents of the reactor maintained at 80°C with continuous agitation for 24 hours. After 24 hours, the contents of the reactor were cooled and filtered with a 50 μm filter and transferred to two 18.93 liter plastic lined metal drums. The pH of the nanoparticle dispersion was 5.5 and the nanoparticle concentration was calculated to be 31.3 wt%.

Preparatory Example 3: Carboxylic acid modified SiO₂ nanodispersion

3000 grams of carboxylic acid modified SiO₂ nanodispersion (Preparatory Example 2) was placed in a 3.78 liter clear glass jar. A Teflon coated stir bar was added to the jar. The jar was placed on a stir plate and agitation initiated. 71.2 grams of aqueous ammonium hydroxide solution, nominally 28 wt%, was added to the nanoparticle dispersion. The contents of the jar were mixed for 20 minutes and then the stir bar was removed from the jar. The pH of the nanoparticle dispersion was 10.0 and the nanoparticle concentration was calculated to be 30.6 wt%.

Preparatory Example 4: NaOH Solution

3000 grams of deionized water was placed in a 3.8 liter clear glass jar. A Teflon coated stir bar was added to the jar. The jar was placed on a stir plate and stirring initiated. 1156 grams of sodium hydroxide (NaOH) pellets were incrementally added to the jar. The NaOH pellets dissolved in the water forming a clear solution that was 28 weight percent NaOH. The Teflon coated stir bar was removed from the jar.

Preparatory Example 5: Preparation of 15 wt% PRIMACOR 5980i aqueous dispersion

1206 grams of deionized water was placed in a 2 liter glass reaction flask. 69 grams of 28 wt% NaOH solution as described in Preparatory Example 4 was added to the flask. Stirring was initiated and 225 grams of PRIMACOR 5980i pellets was added to the flask. The reaction flask which was equipped with a reflux column was heated to 100°C. Within 2.5 hours, the PRIMACOR 5980i pellets dissolved in the basic water solution to form a clear dispersion. The PRIMACOR 5980i dispersion was filtered through a 200 micron filter to give a 75% ammonium neutralized PRIMACOR 5980i dispersion at 15 wt% solids.

Preparatory Example 6: Preparation of 15 wt% SURLYN 9120 aqueous dispersion

27.76 kilograms of deionized water was placed in a 37.85 liter stainless steel reactor. 5.11 kilograms of SURLYN 9120 ionomer was added to the reactor and agitation with a stainless steel blade was initiated at 30 rpm. SURLYN 9120 is a partially neutralized poly(ethylene-co-methacrylic acid) ionomer with a melt flow index (MFI) of 1.3, acid content of 19 weight percent, with 38% neutralization with Zn²⁺ ions. 1.21 kilograms of the 28 weight percent sodium hydroxide (NaOH) aqueous solution from Preparatory Example 4 was added to the reactor. The agitation was increased to 120rpm. The mixture was heated to 150°C and held for 2.5 hours with continuous agitation in the closed (pressurized) reactor. The ionomer dispersed to form a milky white aqueous solution with -15% by weight neutralized SURLYN 9120.

Preparatory Film Substrate Example S1

A film was made by coating the 15wt% PRIMACOR 5980i aqueous dispersion from Preparatory Example 5 on to the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan). The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of -10μm and the film was wound into a roll.

Preparatory Film Substrate Example S2

A film was made by coating the 15wt% SURLYN 9120 aqueous dispersion from Preparatory Example 6 on to the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan). The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of -10μm and the film was wound into a roll.

Preparatory Film Substrate Example S3 A coating solution was made by mixing 1706 grams of the 15wt% dispersion of PRIMACOR 5980i from Preparatory Example 5 and 44 grams of carboxylic acid modified SiO₂ nanodispersion from Preparatory Example 3. A film was made by coating the ionic elastomer nanocomposite dispersion onto the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan). The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of ~10μm and the film was wound into a roll. The dried film had 5wt% 20nm SiO₂ nanoparticles.

Preparatory Film Substrate Example S4

A coating solution was made by mixing 1683 grams of the 15wt% dispersion of PRIMACOR 5980i from Preparatory Example 5 and 67 grams of carboxylic acid modified SiO₂ nanodispersion from Preparatory Example 3. A film was made by coating the ionic elastomer nanocomposite dispersion onto the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan. The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of ~10μm and the film was wound into a roll. The dried film had 7.5wt% 20nm SiO₂ nanoparticles.

Preparatory Film Substrate Example S5

A coating solution was made by mixing 1706 grams of the 15wt% dispersion of SURLYN 9120 from Preparatory Example 6 and 44 grams of carboxylic acid modified SiO₂ nanodispersion from Preparatory Example 3. A film was made by coating the ionic elastomer nanocomposite dispersion onto the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan. The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of ~ 10μm and the film was wound into a roll. The dried film had 5wt% 20nm SiO₂ nanoparticles.

Preparatory Film Substrate Example S6 A coating solution was made by mixing 1683 grams of the 15wt% dispersion of SURLYN 9120 from Preparatory Example 6 and 67 grams of carboxylic acid modified SiO₂ nanodispersion from Preparatory Example 3. A film was made by coating the ionic elastomer nanocomposite dispersion onto the unprimed side of a 75 μm polyester substrate (PET). The dispersion was applied to the PET substrate in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness was controlled by the use of a metering pump and a mass flow meter and solution was filtered through a Roki HT-40 filter (ROKI TECHNO Co., Ltd., Tokyo, Japan). The volatile components of the dispersion were removed by drying in a three-zone air flotation zoned oven (ovens temperatures set to 66°C, 93°C and 135°C). The dried coating had a thickness of ~10μm and the film was wound into a roll The dried film had 7.5wt% 20nm SiO₂ nanoparticles.

Preparatory Film Substrate Examples PU7-PU17

Aliphatic Polyurethane Film Preparative Intermediates PU7-PU17

Samples of shape memory polyurethane (PU) were prepared in a roll to roll process where the isocyanate and polyol with catalyst were mixed using an inline dynamic mixer. The solutions were applied to a moving web between two silicone release liners at an appropriate flow rate to achieve the desired final sample thickness. The polyurethane between films were heated at 70°C and wound into a roll. The films were postbaked at 70°C for 24 hours prior to lamination to glass. Samples had a range of equivalents ofNCO reacted with 1.0 equivalents of -OH, as shown in Table 2 in order to achieve the desired glass transition temperature and crosslink concentration. Relative proportions by mass of Polyol 1 and Polyisocyanate 1 for intermediate films PU7-PU 12 are shown in Table 2. The coated materials contained about 350ppm dibutyltin dilaurate catalyst.

Table 2: Coating compositions and theoretical crosslink concentration

Polyurethane Film Preparative Intermediates PU13-PU16

The polyurethanes for Examples PU13 - PU 16, were composed of a polyol 1 (K-FLEX 188) reacted with a blend of multifunctional isocyanates, Polyisocyanate 1 and Polyisocyanate 2, prepared in the same manner as samples PU7-PU12. The weight ratio Polyol 1 to Polyisocyanate 1 to Polyisocyanate 2 for samples PU13-PU16 are shown in Table 3. Polyisocyanate 2 contains a uretdione unit that can react with excess OH in the polyol component at elevated temperature to form an allophanate group. For this reason, the table contains two stoichiometric ratio columns. The first calculates the NCO/OH ratio based on only existing NCO content in Polyisocyanate 1 and Polyisocyanate 2 at the beginning of the reaction. The NCO+UD/OH ratio accounts for the ratio after the uretdione is reacted with excess OH of the polyol. The theoretical gel content and crosslink concentration are reported in Table 3.

Table 3: Mix ratios for polyurethanes for Examples PU 13-PU16

Polyurethane Film Preparative Intermediate PU17 Polyurethane Substrate intermediate PU17 coating was made with an alternative polyol, Fomrez

55-112 in order to provide a film having a lower glass transition temperature. The polyurethane was composed of polyol 2 reacted with Polyisocyanate 1, prepared in the same manner as samples PU7-PU12. The weight ratio Polyol 2 to Polyisocyanate 1 for sample PU17 is shown in Table 4. Ovens were run at 70°C and the samples were post-cured for 24 hours at 70°C

Table 4: Coating composition and theoretical crosslink concentration

Polyurethane Film Intermediates Characterization The glass transition temperature of the polyurethane coatings was characterized using Q800 DMA from TA Instruments. Samples were cut into strips 6.35 mm wide and about 4 cm long. The thickness of each film was measured. The films were mounted in the tensile grips of a Q800 DMA from TA Instruments with an initial grip separation between 16 mm and 19 mm. The samples were then tested at an oscillation of 0.2% strain and 1 Hz throughout a temperature ramp from -50 °C to 200 °C at a rate of 2 °C per minute. The results are shown in Table 5. The onset of the glass transition was determined by DSC and by location of peak for E". The temperature at which the Tan Delta signal reached a maximum was recorded as the peak Tan Delta temperature. Table 5: Thermal and mechanical properties of the coatings alone

Preparatory Film Substrate Example S7 - S17

Preparative examples S7 - S17 are made using a procedure similar to that described for polyurethane intermediate films PU7 - PU17. Samples of shape memory polyurethane are prepared in a roll to roll process where the isocyanate and polyol with catalyst were mixed using an inline dynamic mixer. The solutions are applied to a moving web between a silicone release liners and an approximately 10 μm thick ionic elastomer nanocomposite coating from preparatory film substrate S5 on unprimed PET, where the surface of the Ionic elastomer nanocomposite is activated with an atmospheric plasma. The mixed solutions are delivered at an appropriate flow rate to achieve the desired final sample thickness of -100 μm of shape memory polyurethane. The polyurethane between films are heated at 70°C and wound into a roll. The films are post-baked at 70°C for 24 hours prior to lamination to glass. Samples have a range of equivalents of NCO reacted with varying equivalents of -OH, that correspond to mix ratios detailed in Tables 2, 3, and 4 in order to achieve the desired glass transition temperature and crosslink concentration for the polyurethane. The polyurethane is expected to bond strongly with the activated surface of the ionic elastomer film on PET. The PET is removed to give a composite two layer Film substrate where the Ionic elastomer nanocomposite from preparatory film substrate S5 in disposed directly onto the polyurethane. Table 6 shows the Preparatory Substrate Films S7 - S17 along with the polyurethane compositions which are related to the compositions of polyurethane intermediate films PU7- PU17, respectively. The coated materials contain about 350ppm dibutyltin dilaurate catalyst.

Table 6: Preparatory Substrate Examples S7 - S17 (Properties of the polyurethane layer)

Preparatory Substrate Example S18 Preparative example S18 is made using a procedure similar to that described for polyurethane intermediate films PU7 - PU17. A sample of shape memory polyurethane with an NCO/OH ratio of 1.05 is prepared in a roll to roll process where the isocyanate and polyol with catalyst are mixed using an inline dynamic mixer. The solutions are applied to a moving web between a silicone release liners and an approximately 10 μm thick ionic elastomer coating from preparatory film substrate S2 on unprimed PET, where the surface of the Ionic elastomer nanocomposite is activated with an atmospheric plasma. The mixed solutions are delivered at an appropriate flow rate to achieve the desired final sample thickness of -100 μm of shape memory polyurethane. The polyurethane between films are heated at 70°C and wound into a roll. The films are post-baked at 70°C for 24 hours prior to lamination to glass. The polyurethane is expected to bond strongly with the activated surface of the ionic elastomer film on PET. The PET is removed to give a composite two-layer film substrate S18 where the Ionic elastomer nanocomposite from preparatory film substrate example S2 is disposed directly onto the polyurethane. The coated materials contain about 350ppm dibutyltin dilaurate catalyst.

Preparatory Substrate Example S19

A melt-processed monolithic nanocomposite film with a composition of 5wt% 20nm SiO₂ nanoparticles 95wt% SURLYN 9120 was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 50.0 grams of the coating from Preparatory Film Substrate Example S3 is removed from the PET substrate, and is added to the preheated Plasti-corder and the material is processed for 15 minutes at 150°C and 75 rpm to form a nanocomposite blend. After processing the melt-processed polymer blend, the material is cooled to room temperature. A portion of the melt-processed material is pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt- processed film is placed between two layers of polyimide film which are between two polished aluminum plates. To press the samples, the melt-processed material was pressed to 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film is removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets are removed once the film sufficiently cooled. The thickness of the pressed film is ~100 microns and the film is expected to have a Transmission of >92%, Haze of < 4.0%, and Clarity of >90%. This pressed film example demonstrates the properties of the film. A film of controlled thickness, for example a film having a thickness of 100 microns, may be made via known extrusion casting and orientation methods to produce rolls of monolithic film which can be used in roll to roll processing.

A sample of shape memory polyurethane with an NCO/OH ratio of 1.05 is prepared in a roll to roll process where the isocyanate and polyol with catalyst are mixed using an inline dynamic mixer. The solutions are applied to a moving web between a silicone release liners and an approximately 100 μm thick ionic elastomer nanocomposite film as described above with 5wt% 20nm SiO₂ nanoparticles. The surface of the Ionic elastomer nanocomposite is activated with an atmospheric plasma. The mixed solutions are delivered at an appropriate flow rate to achieve the desired final sample thickness of -100 μm of shape memory polyurethane. The polyurethane between films are heated at 70°C and wound into a roll. The films are post-baked at 70°C for 24 hours prior to lamination to glass. The polyurethane is expected to bond strongly with the activated surface of the ionic elastomer film on PET. The PET is removed to give a composite two-layer film substrate S19 where the 100 μm ionic elastomer nanocomposite is disposed directly onto the polyurethane. The coated materials contain about 350ppm dibutyltin dilaurate catalyst.

Preparatory Substrate Example S20

A melt-processed monolithic nanocomposite film with a composition of 20wt% 20nm SiO₂ nanoparticles 80wt% SURLYN 9120 was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 25.0 grams of the coating from Preparatory Film Substrate Example S2 was removed from the PET substrate, along with 25.0 grams of SURLYN 9120 pellets were added to the preheated Plasti-corder and the materials were processed for 15 minutes at 150°C and 75 rpm to form a nanocomposite blend. After processing the melt-processed polymer blend was cooled to room temperature. A portion of the melt-processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt- processed material was pressed to 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 8.7 mil (-221 microns) and the film had a Transmission of 92.8%, Haze of 3.8%, and Clarity of 93.7%. This pressed film example demonstrates the properties of the film. A film of controlled thickness, for example a film having a thickness of 100 microns, may be made via known extrusion casting and orientation methods to produce rolls of monolithic film which can be used in roll to roll processing.

Preparatory Film Substrate Example S21

A melt-processed monolithic film of a SURLYN 9120 ionomer was prepared using a Plasti- corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 50.0 grams of SURLYN 9120 pellets was added to the preheated Plasti-corder and was processed for 15 minutes at 150°C and 75 rpm. After processing the melt-processed material was cooled to room temperature. A portion of the melt-processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt-processed material was pressed to 900 kg at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 7.1 mil (-180 microns) and the film had a Transmission of 92.3%, Haze of 3.5%, and Clarity of 96.8%. Films of controlled thickness may be made via known extrusion casting and orientation methods to produce rolls of monolithic film at thickness from 25-250 microns. Preparatory Film Substrate Example S22

A melt-processed monolithic film of a 44wt% PRIMACOR 5980i and 56% SURLYN 9120 ionomer was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 22.0 grams of PRIMACOR 5980i pellets and 28.0 grams SURLYN 9120 pellets were added to the preheated Plasti-corder and the materials were processed for 15 minutes at 150°C and 75 rpm to form a blend. After processing the melt-processed polymer blend was cooled to room temperature. A portion of the melt-processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt-processed material was pressed to 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 6.5 mil (~165 microns) and the film had a Transmission of 92.4%, Haze of 3.1%, and Clarity of 97.1%. Films of controlled thickness may be made via known extrusion casting and orientation methods to produce rolls of monolithic film at thickness from 25-250 microns.

Preparatory Film Substrate Example S23

A melt-processed monolithic nanocomposite film with a composition of 20wt% 20nm SiO₂ nanoparticles 40wt% SURLYN 9120 and 40wt%NUCREL 699 was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 25.0 grams of the coating from Preparatory Film Substrate Example S2 was removed from the PET substrate, along with 5.0 grams of SURLYN 9120 pellets and 20.0 grams of NUCREL 699 pellets were added to the preheated Plasti-corder and the materials were processed for 15 minutes at 150°C and 75 rpm to form a nanocomposite blend. After processing the melt-processed polymer blend was cooled to room temperature. A portion of the melt- processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt-processed material was pressed with 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 7.7 mil (~196 microns) and the film had a Transmission of 93.0%, Haze of 3.4%, and Clarity of 94.3%. Films of controlled thickness may be made via known extrusion casting and orientation methods to produce rolls of monolithic film at thickness from 25-250 microns. Preparatory Film Substrate Example S24

A melt-processed monolithic nanocomposite film with a composition of 20wt% 20nm SiO₂ nanoparticles 40wt% SURLYN 9120 and 40wt% PRIMACOR 1410 was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 25.0 grams of the coating from Preparatory Film Substrate Example S2 was removed from the PET substrate, along with 5.0 grams of SURLYN 9120 pellets and 20.0 grams of PRIMACOR 1410 pellets were added to the preheated Plasti-corder and the materials were processed for 15 minutes at 150°C and 75 rpm to form a nanocomposite blend. After processing the melt-processed polymer blend was cooled to room temperature. A portion of the melt- processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt-processed material was pressed to 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 11.3 mil (~287 microns) and the film had a Transmission of 91.2%, Haze of 3.6%, and Clarity of 96.1%. Films of controlled thickness may be made via known extrusion casting and orientation methods to produce rolls of monolithic film at thickness from 25-250 microns.

Preparatory Film Substrate Example S25

A melt-processed monolithic nanocomposite film with a composition of 20wt% 20nm SiO₂ nanoparticles 40wt% SURLYN 8150 and 40wt% SURLYN 9020 was prepared using a Plasti-corder (C.W. Brabender Instruments, Inc., South Hackensack, NJ). 25.0 grams of the coating from Preparatory Film Substrate Example S5 was removed from the PET substrate, along with 5.0 grams of SURLYN 8150 pellets and 20.0 grams of SURLYN 9020 (terpolymer) pellets were added to the preheated Plasti- corder and the materials were processed for 15 minutes at 150°C and 75 rpm to form a nanocomposite blend. After processing the melt-processed polymer blend was cooled to room temperature. A portion of the melt-processed material was pressed into a film using an Auto Series Hot Press (Carver Inc., Wabash, IN). A portion of the melt-processed film was placed between two layers of polyimide film which were between two polished aluminum plates. To press the samples, the melt-processed material was pressed to 900 kg force at 125°C and held for 5 minutes. The sample was then pressed to 10900 kg force at 125°C and held for 0.1 minutes (6 seconds). The pressed film was removed from the press and from between the aluminum plates and cooled to room temperature. The polyimide sheets were removed once the film sufficiently cooled. The thickness of the pressed film was 3.5 mil (~89 microns) and the film had a Transmission of 93.4%, Haze of 3.6%, and Clarity of 94.7%. Films of controlled thickness may be made via known extrusion casting and orientation methods to produce rolls of monolithic film at thickness from 25-250 microns.

Examples 1-10

Examples 1-10 were made by plasma processing techniques of the ionic elastomer and ionic elastomer nanocomposite coatings in Film Substrate Examples S1-S6. General plasma processing techniques can be found in U.S. Pat. No. 5,888,594 (David et al.) and U.S. Pat. Appl. Pub. No. 2017/0067150 (David et al.). Plasma treatment was carried out by using a homebuilt plasma treatment system described in detail in U.S. Pat. No. 5,888,594 (David et al.) with some modifications. The width of the drum electrode was increased to 42.5 inches (108 cm) and the separation between the two compartments within the plasma system was removed so that all the pumping was carried out by means of the turbo-molecular pump and thus operating at a process pressure of around 1-50 mTorr.

Each Film was mounted in a roll to roll fashion within the chamber. The film was mounted such that the surface of the Ionic elastomer or ionic elastomer nanocomposite was exposed to the atmosphere. The PET was wrapped around the drum electrode and was secured to the take up roll on the opposite side of the drum. The unwind and take up tensions were at 81bs (36 N) and 141bs (62 N), respectively. The chamber door was closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber were carried out by moving the substrates back and forth enabling multiple treatments on the same samples. The input film thicknesses in each case were ~85μm for the samples; 75μm for the PET substrate and 10μm for the ionic elastomer and ionic elastomer nanocomposite coatings. Specific plasma processing conditions for each example are shown in Table 7. Results are presented in Tables 8A and 8B. Processing conditions similar to those of examples 1 to 10 applied to polymeric films and polymeric films incorporating 20nm particles is known to result in nanostructures having a diameter of roughly 10-100 nanometers, and height of roughly 200-800 nanometers. Each of these samples is left with a trimethylsilyl terminated surface giving superhydrophobic surfaces.

Comparative Examples C1-C6:

Samples of Preparative Substrate Films S1 - S6 were provided as comparative examples C1-C6, where the Substrate Films S1-S6 were measured with no plasma treatment. Data for films S1-S6 is shown in Table 8 A and 8B. Table 7: Plasma Processing Conditions for Example 1-10

Table 8A: Fluid Contact Angles for Examples 1-10 and C1-C6

Table 8B: Optical Data for Examples 1-10 and C1-C6

Examples 11-24

Examples 11-24 were made by plasma processing techniques of the ionic elastomer and ionic elastomer nanocomposite coatings in Film Substrate Examples S1-S6. General plasma processing techniques can be found in U.S. Pat. No. 5,888,594 (David et al.) and U.S. Pat. Appl. Pub. No. 2017/0067150 (David et al.). Plasma treatment was carried out by using a homebuilt plasma treatment system described in detail in U.S. Pat. No. 5,888,594 (David et al.) with some modifications. The width of the drum electrode was increased to 42.5 inches (108 cm) and the separation between the two compartments within the plasma system was removed so that all the pumping was carried out by means of the turbo-molecular pump and thus operating at a process pressure of around 1-50 mTorr.

Each Film was mounted in a roll to roll fashion within the chamber. The film was mounted such that the surface of the Ionic elastomer or ionic elastomer nanocomposite was exposed to the atmosphere. The PET was wrapped around the drum electrode and was secured to the take up roll on the opposite side of the drum. The unwind and take up tensions were at 8lbs (36 N) and 14lbs (62 N), respectively. The chamber door was closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber were carried out by moving the substrates back and forth enabling multiple treatments on the same samples. The input film thicknesses in each case were ~85 μm for the samples; 75μm for the PET substrate and 10μm for the ionic elastomer and ionic elastomer nanocomposite coatings. Specific plasma processing conditions for each example are shown in Table 9. Results are presented in Tables 5A and 5B. Processing conditions similar to those of examples 11 to 24 applied to polymeric films and polymeric films incorporating 20nm particles is known to result in nanostructures having a diameter of roughly 10-100 nanometers, and height of roughly 200-800 nanometers. As seen in Table 9 for each sample, the last two passes are used to deposit a thin carbon containing silica layer (DLG layer, steps 3 and 4 for some samples, and steps 4 and 5 for other samples). This silica layer was provided for adhesion. Table 9: Plasma Processing Conditions for Examples 11-24

After etching and the application of a thin carbon containing silica layer (DLG layer) for adhesion, one of four fluorosilane coating solutions FCS1 through FCS 4 was applied to the surface of each film. The fluorosilane coating solution compositions were made by adding ECC-1000, followed by 85/15 TFT/EtOH, and then catalyst solution to glass vials in the proportions in Table 10 below.

Table 10: Fluorosilane coating solutions FCS1 - FCS4

For each of the substrates with DLG layer shown in Table 4 (Examples 11-24) a single solution was used to coat the substrates by drawdown coating using a #4 Mayer Rod (0.0004" (10μm) approximate wet film thickness) from Diversified Enterprises, Claremont NH. The coatings were baked in an oven at 90° C for 5 minutes after coating. The approximate thicknesses of the coatings are shown in table 11 below. For all examples coatings were performed within 6 hours of mixing the solutions.

Table 11: Fluorosilane coating solution

Table 12 shows which coating solution was used to produce each of Examples 11-24 and data for fluid contact angle and optical properties. Data for comparative sample is shown again for ease of comparison where C1-C6 correspond to preparatory film substrates S1-S6 respectively, where no etching or overcoat treatment was performed. An additional comparative sample C7 is also provided which corresponds to data for the in-process Example 11 where the DLG surface was not overcoated with a fluorosilane coating solution. Table 12: Data for Examples11-24 and Comparative Examples C1-C6

Example 25: Shape Memory Polyurethane Substrate with Ionic Elastomer Nanocomposite (IENC)

An omniphobic film is made by plasma processing techniques of the ionic elastomer nanocomposite coating on shape memory polyurethane using Preparatory Film Substrate Example S7 as described for Examples 1-10 above.

The film which is ~ 162 μm in thickness (52 μm silicone release liner, ~100 μm polyurethane layer and an ~10 μm ionic elastomer nanocomposite layer) is mounted in a roll to roll fashion within the chamber. The film is mounted such that the surface of the ionic elastomer nanocomposite is exposed to the atmosphere. The film is wrapped around the drum electrode and was secured to the take up roll on the opposite side of the drum. The unwind and take up tensions are at 81bs (36 N) and 141bs (62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth enabling multiple treatments on the same samples. Specific plasma processing conditions are shown in Table 13.

Table 13: Plasma Processing conditions for making nanostructured film with DLG surface

The DLG coated nanostructured film is coated by drawdown coating using a #4 Mayer Rod (0.0004" (lOum) approximate wet film thickness) from Diversified Enterprises, Claremont NH using fluorosilane coating solution FCS2 details of which are found in Tables 10 and 11. The coating is baked in an oven at 90° C for 5 minutes after coating. The estimated thickness of the coating is 34nm. The final film is expected to be omniphobic exhibiting advancing water contact angle of >145°, receding water contact angle >100°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

Example 26: Shape Memory Polyurethane Substrate with Ionic Elastomer An ominphobic film is made by plasma processing techniques of the ionic elastomer coating on shape memory polyurethane using Preparatory Film Substrate Example S18 as described for Examples 1-10 above.

The film which is ~ 162 μm in thickness (52 μm silicone release liner, ~100 μm polyurethane layer and an ~10 μm ionic elastomer layer) is mounted in a roll to roll fashion within the chamber. The film is mounted such that the surface of the ionic elastomer is exposed to the atmosphere. The film is wrapped around the drum electrode and was secured to the take up roll on the opposite side of the drum. The unwind and take up tensions are at 81bs (36 N) and 141bs (62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth enabling multiple treatments on the same samples. Specific plasma processing conditions are shown in Table 14.

Table 14: Plasma Processing conditions for making nanostructured film with DLG surface

The DLG coated nanostructured film is coated by drawdown coating using a #4 Mayer Rod (0.0004" (10 μm) approximate wet film thickness) from Diversified Enterprises, Claremont NH using fluorosilane coating solution FCS1 details of which are found in Tables 10 and 11. The coating is baked in an oven at 90° C for 5 minutes after coating. The estimated thickness of the coating is 18nm.

The final film is expected to be omniphobic exhibiting advancing water contact angle of >145°, receding water contact angle >100°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

Example 27: IENC Substrate An ominphobic film is made by plasma processing techniques of the ionic elastomer nanocomposite coating on shape memory polyurethane using Preparatory Film Substrate Example S19 as described for Examples 1-10 above.

The film, which is a monolithic ionic elastomer nanocomposite having 5 wt% 20 nm silica nanoparticles, has a thickness of -100 μm is mounted in a roll to roll fashion within the chamber. The film is mounted such that the surface of the one side of the ionic elastomer nanocomposite is exposed to the atmosphere. The film is wrapped around the drum electrode and was secured to the take up roll on the opposite side of the drum. The unwind and take up tensions are at 81bs (36 N) and 141bs (62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth enabling multiple treatments on the same samples. Specific plasma processing conditions are shown in Table 15.

Table 15: Plasma Processing conditions for making nanostructured film with DLG surface

The DLG coated nanostructured film is coated by drawdown coating using a #4 Mayer Rod (0.0004" (10 μm) approximate wet film thickness) from Diversified Enterprises, Claremont NH using fluorosilane coating solution FCS2 details of which are found in Tables 10 and 11. The coating is baked in an oven at 90° C for 5 minutes after coating. The estimated thickness of the coating is 34nm.

The final film is expected to be omniphobic exhibiting advancing water contact angle of >145°, receding water contact angle >100°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

Example 28: IENC Substrate with HFPO UA HC etched and fluorosilane overcoated

A hardcoat (HC) solution is made by mixing 1 gram of ESACURE ONE, 87.54 grams of HFPO-UA (10% HFPO, 30% solids), 64.78 grams of CN9010 in 97.16 grams of methyl ethyl ketone (Fisher scientific). The solution is stirred until all components were dissolved. The resulting solution is essentially homogeneous with a clear appearance. The hardcoat solution is applied to Preparatory Film Substrate S20 in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness is controlled by the use of a metering pump and a mass flow meter. The volatile components of the coating are removed by drying in a three- zone air floatation zone oven (ovens temperatures set to 60°C, 71°C, 82°C). The dried coating is cured with an in-line 600 W/in Fusion UV curing station with a dichroic reflector, H bulb, nitrogen inerting, at 100% Power and with backup roll temperature set to 43°C. The cured coating on Preparatory Film Substrate S20 has a thickness of approximately 5 μm and the film is wound into a roll.

The HC on Preparatory Film S20 is then processed using plasma processing techniques as described in example 1-10 above. The roll of HC on Film S20 is mounted within the chamber such that the hardcoat (HC) surface is exposed to atmosphere; i.e., the HC surface is opposite the surface of the drum electrode. The film is wrapped around the drum electrode and is secured to the take up roll on the opposite side of the drum. The unwind and take-up tensions are 8 and 14 lbs. (36 and 62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth, enabling multiple treatments on the same samples.

The film thickness is ~105 μm; ~ 100μm for substrate S20 and -5 μm for the hardcoat layer.

Specific plasma processing conditions are shown in Table 16.

Table 16: Plasma Processing Conditions for Example 28

After etching (plasma passes 1-3) and the application of a thin carbon containing silica layer (DLG layer, in plasma passes 4 and 5) for adhesion, a fluorosilane solution is prepared by mixing 7 grams ECC-1000, 418.8 g alpha, alpha, alpha-trifluorotoluene (Acres Organics, Morris Plains, N.J.), 70 g dry ethanol (200 proof from Koptec, King of Prussia, PA), and 4.2 grams of a 5 wt % solution of para-toluenesulfonic acid monohydrate (Alfa Aesar, Tewksbury, MA) in ethanol (200 proof from Koptec, King of Prussia, PA). The solution is applied to the above hardcoated/etched/DLG film in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a syringe pump. The volatile components of the coating are dried in a two-zone oven (oven temperatures set to 93°C, 93°C ) to give a very thin coating over the nanostructured surface with an approximate overcoat thickness of from about 50nm - 90nm. The film is wound into a roll. A protective liner/premask (Tredegar RS-011118-14) was applied individually to 3 ft (0.9 m) cut sections of the film using a hand laminator.

The final film is expected to be omniphobic exhibiting advancing water contact angle of >150°, receding water contact angle >110°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

Example 29: IENC Substrate with HFPO UA HC etched and fluorosilane overcoated with POS-1 antistat

An anti-static solution is made by mixing 1 gram of ESACURE ONE, 15.84 grams of POS-1 (Polymerizable Onium Salt 1), 23.76 grams of SR9035 in 120 grams of methyl ethyl ketone and 40 grams of isopropyl alcohol (Fisher scientific). The solution is stirred until all components are dissolved. The resulting solution is essentially homogeneous with a clear appearance. The anti-static solution is applied to Film S20 in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a metering pump and a mass flow meter. The volatile components of the coating are removed by drying in a 3 zone air floatation zone oven (ovens temperatures set to 60°C, 71°C, 82°C). The dried coating is cured with an in-line 600 W/in Fusion UV curing station with a dichroic reflector, H bulb, nitrogen inerting, and with backup roll temperature set to 43°C. The cured coating is approximately 5 μm thick and film was wound into a roll.

Next, a hardcoat solution is made by mixing 1 gram of ESACURE ONE, 87.54 grams of HFPO-UA (10% HFPO, 30% solids), 64.78 grams of CN9010 in 87.75 grams of methyl ethyl ketone (Fisher scientific) and 9.4 lg of cyclopentanone. The solution is stirred until all components are dissolved. The resulting solution is essentially homogeneous with a clear appearance. The hardcoat solution is applied to the conductive polymer layer in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a metering pump and a mass flow meter. The volatile components of the coating are removing by drying in a three-zone air floatation zone oven (ovens temperatures set to 60°C, 71°C, 82°C). The dried coating is cured with an in-line 600 W/in Fusion UV curing station with a dichroic reflector, H bulb, nitrogen inerting, and with backup roll temperature set to 43°C. The cured coating is approximately 5μm thick and the film was wound into a roll.

The HC on Film S20 was then processed using general plasma processing techniques as described previously. The roll of HC on Film S20 is mounted within the chamber such that the hardcoat (HC) surface is exposed to atmosphere; i.e., the HC surface is opposite the surface of the drum electrode. The film is wrapped around the drum electrode and is secured to the take up roll on the opposite side of the drum. The unwind and take-up tensions are 8 and 14 lbs. (36 and 62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth, enabling multiple treatments on the same samples. The film thickness is ~110μm; 100μm for Ionic Elastomer Substrate S20, ~5μm for the POS-1 antistat layer and an ~5μm hardcoat layer. Specific plasma processing conditions are shown in Table 17.

Table 17: Plasma Processing Conditions for Example 29

After etching and the application of a thin DLG layer for adhesion, a fluorosilane solution is prepared by mixing 7 grams ECC-1000, 418.8 g alpha, alpha, alpha-trifluorotoluene (Acres Organics, Morris Plains, N.J.), 70 g dry ethanol (200 proof from Koptec, King of Prussia, PA), and 4.2 grams of a 5 wt % solution of para-toluenesulfonic acid monohydrate (Alfa Aesar, Tewksbury, MA) in dry ethanol ((200 proof from Koptec, King of Prussia, PA). The solution is applied to the above hardcoated/etched/DLG film in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a syringe pump. The volatile components of the coating is removed by drying in a two-zone oven (oven temperatures set to 93°C, 93°C). The dried and cured coating has a thickness of approximately 100 nm.

The final film is expected to be omniphobic exhibiting advancing water contact angle of >150°, receding water contact angle >100°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

The addition of the antistat layer to this construction is expected to result in improved resistance to pinning of water droplets on the surface of the film from fine misting water and the sample also is expected to demonstrate improved performance is resisting ice build up for sleet. It is expected that water droplets in contact angle measurement for the as made protective film roll off freely and water sprayed at the surface bounces off of the surface with little to no sticking of small water droplets.

Example 30: IENC Substrate with HFPO UA HC etched and fluorosilane overcoated with PEDOT antistat

A conductive polymer solution is made by mixing 21.6 g of CLEVIOS P conductive polymer premix which is 40% in DI water (Heraeus, Hanau, Germany), 4.3 g Tomadol 25-9 premix, which is 60.6% in DI water (Evonik Industries, Essen, Germany), 4.3 g N-Methyl-2- Pyrrolidone (Sigma-Aldrich) and 1169.6 g DI water. The solution is stirred until all components are dissolved. The resulting solution is essentially homogeneous with a dark blue appearance. The conductive polymer solution is applied to Preparatory Film Substrate S20 in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a metering pump and a mass flow meter. The volatile components of the coating are removed by drying in a three-zone air floatation zone oven (ovens temperatures set to 60°C, 71°C, 82°C The Conductive coating has a thickness of approximately 18-20nm film and is wound into a roll.

Next, a hardcoat solution is made by mixing 1 gram of ESACURE ONE, 87.54 grams of HFPO-UA (10% HFPO, 30% solids), 64.78 grams of CN9010 in 97.16 grams of methyl ethyl ketone (Fisher scientific). The solution is stirred until all components were dissolved. The resulting solution is essentially homogeneous with a clear appearance. The hardcoat solution is applied to the conductive polymer layer in a roll to roll process where the solution was metered through a slot die onto the moving web. Thickness is controlled by the use of a metering pump and a mass flow meter. The volatile components of the coating are removed by drying in a three- zone air floatation zone oven (ovens temperatures set to 60°C, 71°C, 82°C). The dried coating is cured with an in-line 600 W/in Fusion UV curing station with a dichroic reflector, H bulb, nitrogen inerting, and with backup roll temperature set to 43°C. The cured coating has a thickness of approximately 5μm and is wound into a roll.

The HC on Film S20 is then processed using general plasma processing techniques as described previously. The roll of HC of Film S20 is mounted within the chamber such that the hardcoat (HC) surface is exposed to atmosphere; i.e., the HC surface is opposite the surface of the drum electrode. The film is wrapped around the drum electrode and is secured to the take up roll on the opposite side of the drum. The unwind and take-up tensions are 8 and 14 lbs. (36 and 62 N), respectively. The chamber door is closed and the chamber pumped down to a base pressure of 5 x 10^-4 torr. Once at pressure, multiple passes through the chamber are carried out by moving the substrates back and forth, enabling multiple treatments on the same samples. The film thickness is ~105μm; ~100μm for substrate S20 and ~5μm for the hardcoat layer, the PEDOT layer having negligible thickness. Specific plasma processing conditions are shown in Table 18.

Table 18: Plasma Processing Conditions for Example 8

After etching and the application of a thin DLG layer for adhesion, a fluorosilane solution is prepared by mixing 7 grams ECC-1000, 418.8 g alpha, alpha, alpha-trifluorotoluene (Acres Organics, Morris Plains, N.J.), 70 g dry ethanol (200 proof from Koptec, King of Prussia, PA), and 4.2 grams of a 5 wt % solution of para-toluenesulfonic acid monohydrate (Alfa Aesar, Tewksbury, MA) in dry ethanol ((200 proof from Koptec, King of Prussia, PA). The solution is applied to the above hardcoated/etched/DLG film in a roll to roll process where the solution is metered through a slot die onto the moving web. Thickness is controlled by the use of a syringe pump. The volatile components of the coating are removed by drying in a two-zone oven (oven temperatures set to 93°C, 93°C). The dried and cured coating has a thickness of approximately 100 nm. The final film is expected to be omniphobic exhibiting advancing water contact angle of >150°, receding water contact angle >100°, and a static water contact angle of > 130°, with a water roll-off angle < 50°, and a hexadecane contact angle of greater than 80°.

The addition of the antistat layer to this construction is expected to result in improved resistance to pinning of water droplets on the surface of the film from fine misting water and the sample also is expected to demonstrate improved performance is resisting ice build up for sleet. It is expected that water droplets in contact angle measurement for the as made protective film roll off freely and water sprayed at the surface bounces off of the surface with little to no sticking of small water droplets.

Test Methods:

Transmission/Haze/Clarity T esting

Luminous transmission, haze, and clarity using a BYK-Gardner Haze-Gard Plus model 4725 (available from BYK-Gardner Columbia, MD). Each result reported in Table 7 is the average of three measurements on a given sample. Samples with obvious optical defects in film preparation were not used in optical testing.

Fluid Contact Angle and Water Roll Off Test Method

Fluid contact angles of each film sample were measured using a Rame-Hart goniometer (Rame-Hart Instrument Co., Succasunna, New Jersey). A Model 500 advanced contact angle goniometer (Rame-hart, Succasunna, NJ) was utilized for contact angle measurements.

Advancing and receding contact angles were measured as described in Korhonen et. al (Langmuir, 2013, 29, 3858-3863).

For all examples and comparative examples, an approximately 1.5” x 3” (3.8 cm x 7.6 cm) sections of the coatings described were cut with a scissors and affixed to the stage of the Instrument.

Fluid was supplied to the surface with the surface at 0° (film in horizontal position) with a volume of 14uL. Measurements were taken at three different spots on each film sample surface, and the reported measurements are the average of the three values for each sample. The probe fluid used in this test was deionized water. The Advancing (θ_adv) and receding (θ_rec) angles were measured based on the values measured during the tilt stage process, where the value was recorded the values reported at the time the droplet started to roll or when the instrument reached an angle of 90° (film in vertical orientation). The water roll off angle was measure when the droplet had moved by more than 10% of it's diameter. Contact Angle hysteresis (θ_hys) was determined using the following equation: θ_hys =θ_adv - θ_rec. The Static contact angle was recorded as the average of the advancing and receding contact angles with the film at 0°. Hexadecane contact angle was measured as a static contact angle at 0°.

The nanostructured film constructions described in the above examples with nanostructured Ionic elastomer and ionic elastomer nanocomposite overcoated with highly fluorinated coatings may use any suitable polyurethane substrate described herein as a base substrate. For examples where a HFPO UA hardcoat is disposed on an ionic elastomer nanocomposite substrate and the HFPO UA HC is etched and overcoated with a highly fluorinated herein may use any suitable Ionic Elastomer Nanocomposite substrate. For example, the substrates described in the Preparatory Film Substrates S21 - S25 may be used.

Terms such as “about” will be understood in the context in which they are used and described in the present description by one of ordinary skill in the art. If the use of “about” as applied to quantities expressing feature sizes, amounts, and physical properties is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, “about” will be understood to mean within 10 percent of the specified value. A quantity given as about a specified value can be precisely the specified value. For example, if it is not otherwise clear to one of ordinary skill in the art in the context in which it is used and described in the present description, a quantity having a value of about 1, means that the quantity has a value between 0.9 and 1.1, and that the value could be 1.

All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.

Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

All references, patents, and patent applications referenced in the foregoing are hereby incorporated herein by reference in their entirety in a consistent manner. In the event of inconsistencies or contradictions between portions of the incorporated references and this application, the information in the preceding description shall control.

Descriptions for elements in figures should be understood to apply equally to corresponding elements in other figures, unless indicated otherwise. Although specific embodiments have been illustrated and described herein, it will be appreciated by those of ordinary skill in the art that a variety of alternate and/or equivalent implementations can be substituted for the specific embodiments shown and described without departing from the scope of the present disclosure. This application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, it is intended that this disclosure be limited only by the claims and the equivalents thereof.

Claims

What is claimed is:

1. A nanostructured article comprising: a substrate; a plurality of first nanostructures disposed on, and extending away from, the substrate, the plurality of first nanostructures comprising at least one polymer, the at least one polymer comprising a first polymer comprising (meth)acrylic acid monomer units; and a covalently crosslinked fluorinated polymeric layer disposed on the plurality of first nanostructures and at least partially filling spaces between the first nanostructures to an average minimum height above the substrate of at least 30 nm such that the polymeric layer comprises a nanostructured surface defined by, and facing away from, the plurality of first nanostructures.

2. The nanostructured article of claim 1, wherein a metal oxide nanoparticle is disposed between the covalently crosslinked fluorinated polymeric layer and a top surface of each first nanostructure in at least a majority of the plurality of first nanostructures.

3. The nanostructured article of claim 1 or 2, wherein the first nanostructures extend to an average height H1 from the substrate and have an average width W1, the nanostructured surface comprising a plurality of second nanostructures having an average peak-to-valley height H2 and an average width W2, H2/W2 being no more than 0.95 H1/W1.

4. The nanostructured article of any one of claims 1 to 3, wherein the nanostructured surface of the covalently crosslinked fluorinated polymeric layer comprises a plurality of second nanostructures, each second nanostructure in at least a majority of the second nanostructures partially surrounding a plurality of the first nanostructures.

5. The nanostructured article of any one of claims 1 to 4, wherein the covalently crosslinked fluorinated polymeric layer is preparable from a composition comprising a fluoropolymer comprising at least one hydrolysable terminal silane group.

6. The nanostructured article of any one of claims 1 to 5, wherein the covalently crosslinked fluorinated polymeric layer is preparable from a composition comprising a fluoropolymer comprising at least two trialkoxysilane terminal groups.

7. The nanostructured article of any one of claims 1 to 6, wherein the nanostructured surface has an advancing water contact angle of at least 130 degrees.

8. The nanostructured article of any one of claims 1 to 6, wherein the nanostructured surface has an advancing hexadecane contact angle of at least 70 degrees.

9. The nanostructured article of any one of claims 1 to 8, wherein the at least one polymer further comprises a second polymer different from the first polymer blended with the first polymer, the second polymer comprising (meth)acrylic acid monomer units.

10. A nanostructured article comprising: a substrate; and a plurality of first nanostructures disposed on the substrate, the plurality of first nanostructures comprising at least one polymer, the at least one polymer comprising a first polymer comprising (meth)acrylic acid monomer units, the plurality of first nanostructures extending away from the substrate along a length of the first nanostructures, the plurality of first nanostructures having an average length L1 and an average width W1, W1 being in a range of 5 nm to 500 nm, L1/W1 being at least 1.

11. The nanostructured article of claim 10, further comprising a covalently crosslinked fluorinated polymeric layer disposed on the plurality of first nanostructures and at least partially filling spaces between the first nanostructures to an average minimum height above the substrate of at least 30 nm such that the polymeric layer comprises a nanostructured surface defined by, and facing away from, the plurality of first nanostructures.

12. A nanostructured article comprising a first layer and a plurality of first nanostructures integrally formed on the first layer, the first layer comprising at least one polymer, the at least one polymer comprising a first polymer comprising (meth)acrylic acid monomer units, the plurality of first nanostructures extending away from the first layer along a length of the first nanostructures, the plurality of first nanostructures having an average length L1 and an average width W1, W1 being in a range of 5 nm to 500 nm, L1/W1 being at least 1.

13. The nanostructured article of claim 12, wherein the first layer further comprises metal oxide nanoparticles dispersed in the at least one polymer, the metal oxide nanoparticles being surface modified with a carboxylic acid silane surface modifying agent.

14. The nanostructured article of claim 12 or 13, wherein the plurality of first nanostructures comprises covalently crosslinked polyurethane having a crosslink concentration in a range from 0.3 to 1.05 mol/kg.

15. The nanostructured article of any one of claim 13 to 14, further comprising a covalently crosslinked fluorinated polymeric layer disposed on the plurality of first nanostructures and at least partially filling spaces between the first nanostructures to an average minimum height above the substrate of at least 30 nm such that the polymeric layer comprises a nanostructured surface defined by, and facing away from, the plurality of first nanostructures.