WO2008118543A2

WO2008118543A2 - Articles having interpenetrating polymer networks and methods of treating articles

Info

Publication number: WO2008118543A2
Application number: PCT/US2008/053215
Authority: WO
Inventors: Sang Beom Lee
Original assignee: Nanodynamics, Inc.
Priority date: 2007-02-06
Filing date: 2008-02-06
Publication date: 2008-10-02
Also published as: WO2008118543A3

Abstract

Articles are provided. Articles may have at least one functional particle in a substrate and at least interpenetrating polymer network. The interpenetrating polymer network inhibits the release of the at least one functional particle from the substrate. Methods of treating articles are further provided.

Description

ARTICLES HAVING INTERPENETRATING POLYMER NETWORKS AND METHODS

OF TREATING ARTICLES

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims priority to and any other benefit of US Provisional Patent Application Serial No. 60/884,454, filed February 6, 2007, the entirety of which is incorporated by reference herein.

BACKGROUND

A variety of nanomaterials with unique size, shape and surface properties have been developed for many applications, such as microelectronics, optics and medical devices. One of the unique properties of nanoparticles is their large surface area, which provides more functional space for catalysis and sensing compared with the surface area of bulk materials. Nanoparticles also exhibit unique surface properties due to their surface-to-volume ratio and the presence of quantum effects, such as the electronic and photo-responsive properties of quantum dots.

Nanomaterials themselves, typically being fine powders, do not possess mechanical strength and cannot be formed into useful macro-scale items. In order to maximize the effect of these properties in actual applications, the nanomaterials are often embedded within, dispersed in or coated on conventional materials. By this process, it is possible to form usable macro-scale devices and products, such as catalysts, coatings, electrodes, dielectrics, fabrics, garments and air filters, which are hybrid composites of macro- and nano-scale materials.

Nanoparticles are small and extremely light, and are readily dispersed as aerosols and suspensions. Accordingly, they must be physically attached to or entrapped within the matrix of the macro-scale device or composition, if they are to remain in place and carry out their desired function for an extended period of time. The fixation of nanomaterials in such substrates serves to extend the working lifetime of the products, and also minimizes any unexpected health and environmental problems that the dispersal of free nanoparticles into the environment might present. For these reasons, the stabilization of nanomaterials dispersed in substrates is highly desirable for many practical applications of nanomaterials. hi the last decade, progress in development of new technology has resulted in textiles and other substrates with enhanced and tailored properties for a variety of applications. A broad range of industries, including the automotive, health care, construction, electronics, military equipment and textile industries, require fabrics or other substrates with improved characteristics.

Among the valuable properties that can be imparted to substrates are: (1) improved stability against mechanical, chemical, photochemical or thermal destruction, e.g., for industrial toxic materials, chemical and biological toxic agents, or as flame resistant agents; (2) improved repellency properties against water, oil and soil; (3) altered light absorption and emission properties from the UV up to the IR region; (4) improved electrical conductivity, e.g. for antistatic and electromagnetic protective properties; (5) immobilization and controlled release of active species, such as biocidal and therapeutic substances; and (6) enhanced barrier properties against harmful or noxious substances.

It has been found that nanoparticles may be difficult to retain in or on a substrate, and a variety of approaches have been used to assist in retaining nanoparticles in or on a substrate. For example, nanoparticles can be embedded in polymeric substrates, and retained physically or by covalent bonding. See for example Ramachandran, T. et al. Antimicrobial textiles. An Overview. IE (I) Journal. TX, 2004, 84, 45-51, Gao. J. et al. J. Am. Chem. Soc. 2005, 127, 3847-3854, Sen, R. et al. Nano Lett. 2004, 4, 459-464, Liu, T. et al. Macromolecules 2004, 37, 7214-7222, Gangopadhyay R. et al Chem. Mater. 2000, 12, 608- 622, Mayer, A. B. R. et al. Polym. Adv. Technol. 2001, 12, 96-106, Jordan, J. et al. Mater. ScL Eng. A 2005, 393, 1-11, Lauter-Pasyuk, V. et al. Langmuir 2003, 19, 7783-7788, Svechnikov, S. V. et al. Russian J. Electrochem. 2004, 40, 259-266, Kumar, T. K. et al. Langmuir 2004, 20, 4733-4737, Zhang, J. et al. Chem. Eur. J. 2004, 10, 3531-3536, Wang, P.-C. et al. J. Polym. ScL: Part A: Polym. Chem. 2004, 42, 5695-5705, Lee, C-F. et al. J. Polym. ScL: Part A: Polym. Chem. 2005, 43, 342-354, Nicholson, P. G. et al. Chem. Commun. 2005, 1052-1054, Yuce, M. Y. et al. Langmuir 2005, 21, 5073-5078, Kedem, S. et al. Langmuir 2005, 21, 5600-5604, Zeng, A. et al. J. Polym. ScL: Part A: Polym. Chem. 2005, 43, 2826-2835, Mallick, K. et al. Mater. ScL Eng. B 2005, 123, 181-186, Murugaraj, P. et al. J. Appl. Phys. 2005, 98, 054304-1-6, Zhang, H. et al. Nature Mater. 2005, 4, 787-793, Tang, E. et al. Colloid Polym. ScL 2006, 284, 422-428, and Zheng, Z. X. et al. Phys. Chem. Comm.. 2001, 21, 1-2. See also, for example, US Patent Application 20050229328, U.S. Pat. No. 6,607,994, Eur. Pat. Appl. 1243688 (2002), U.S. Pat. No 5,641,561, U.S. Pat. No 6,872,424, U.S. Pat. No. 4,174,418, U.S. Pat. No. 4,199,322, and U.S. Pat. No. 4,394,517.

A common drawback of these approaches is that nanoparticles often lose their desirable functional properties upon covalent binding to the surfaces. Surface properties, such as catalytic, optical, absorption and antimicrobial properties, are also susceptible to being attenuated or eliminated when particles are embedded within polymer matrices.

Thus, there remains a need in the art for alternative methods of retaining nanomaterials and other functional particles on or in substrates.

SUMMARY hi accordance with embodiments of the present invention, articles are provided. The articles can comprise a porous substrate having at least one functional particle and an interpenetrating polymer network formed with the substrate. The interpenetrating polymer network comprises at least one interpenetrating polymer network monomer polymerized in the presence of the substrate to form the interpenetrating polymer network with the substrate. The interpenetrating polymer network inhibits release of the at least one functional particle from the substrate. hi accordance with other embodiments, methods for treating articles are provided. The methods can comprise providing a porous substrate, at least one functional particle, and at least one interpenetrating polymer network monomer and polymerizing the at least one interpenetrating polymer network monomer such that an interpenetrating polymer network is formed whereby release of the at least one functional particle from the porous substrate is inhibited.

It will be understood that these and other embodiments are included in the scope of the present invention.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The following detailed description of embodiments of the present invention can be best understood when read in conjunction with the following drawings, where like structure is indicated with like reference numerals and in which:

Figure 1 shows a schematic representation an article having an interpenetrating polymer network;

Figure 2 shows a schematic representation of a method of treating an article;

Figure 3 shows a schematic representation of another method of treating an article;

Figure 4 shows various solutions obtained from extensive washings of differently treated cellulose filter paper and textile samples embedded with halloysite nanotubes or silver nanoparticles; (A) are solutions obtained from washings with cellulose and textile samples containing halloysite nanotubes with no chitosan or no interpenetrating polymer network ("IPN") at all. (B) are solutions obtained from washings with samples containing the halloysite nanotubes embedded filter paper and textiles samples using chitosan for which no intentional curing/crosslinking of chitosan has been done and (C) are solutions obtained from washing cured/crosslinked IPN stabilized / immobilized silver nanoparticle samples where chitosan was used as the polymer for the formation of IPN. Pictured from left to right are solutions obtained from using the same extensive washing and sonication procedure for all of samples with the various levels of IPN treatments described above. Pictured horizontally are solutions taken from washing and sonication using various types of cellulosic and textile samples. The cloudiness in the various solutions provides an indication of the level of stabilization / immobilization of the nanomaterial on the surface. The clearer the solution the lesser amount of halloysite nanotubes that have been removed from the surface due to the washing procedure, thus the more stabilization / immobilization the nanomaterial on the surface; and

Figure 5 shows the zone of inhibition of medium-density fiberboard (MDF) coated with fungicide-impregnated halloysite and the zone of inhibition of MDF coated with a commercial biocide, Fungitrol 720 (available from International Specialty Products, Wayne, NJ US).

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION The present invention will now be described with occasional reference to the specific embodiments of the invention. This invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for describing particular embodiments only and is not intended to be limiting of the invention. As used in the description of the invention and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. AU publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety.

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth as used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless otherwise indicated, the numerical properties set forth in the following specification and claims are approximations that may vary depending on the desired properties sought to be obtained in embodiments of the present invention. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical values, however, inherently contain certain errors necessarily resulting from error found in their respective measurements.

In accordance with embodiments of the present invention, articles are provided. In accordance with other embodiments of the present invention, methods of treating articles are provided.

In some embodiments, articles are provided. The articles comprise a porous substrate having at least one functional particle and an interpenetrating polymer network formed with the substrate. The interpenetrating polymer network comprises at least one interpenetrating polymer network monomer polymerized in the presence of the porous substrate to form the interpenetrating polymer network with the substrate. The interpenetrating polymer network inhibits release of the at least one functional particle from the substrate. In some examples, the interpenetrating polymer network may be intertwined with the functional particles, and this intertwining may inhibit the release of the functional particles from the porous substrate, hi some examples, the functional particle may be in the substrate.

For purposes of describing and defining the present invention, the term "in the substrate" shall be understood as referring to a functional particle that is on or in the substrate. Further, for purposes of describing and defining the present invention, the term "inhibits release" shall be understood as meaning the functional particles being retained in the substrate for a period of time, under normal usage conditions, that is greater than the period of time that the particles are retained in the substrate in the absence of the interpenetrating polymer network. Thus, the interpenetrating polymer network may inhibit the release of or the leaching of functional particles from the substrate.

Additionally, for purposes of describing and defining the present invention, the term "interpenetrating polymer network" ("EPN") shall be understood as referring to a system in which an interpenetrating network monomer or monomers are polymerized in the presence of a porous and/or textured substrate such that the resulting polymer or polymers are intertwined/interlocked with at least a portion of the porous substrate. Further, for purposes of describing and defining the present invention, the term "interpenetrating polymer network monomer" shall refer to any monomer or polymer subunit suitable for use in forming an interpenetrating polymer network and that contains reactive groups that may react with each other to crosslink. The reactive groups may or may not react with the porous substrate. Yet further, for purposes of describing and defining the present invention, the term "interpenetrating polymer network monomer" shall be understood as excluding monomers that self assemble.

The porous substrate may be any suitable porous and/or textured substrate. For example, the substrate may be selected from fibers, yarns, porous textiles, carpeting, retractable awnings, outdoor fabrics, polymeric surfaces, and porous membranes, or combinations thereof. In other examples, the substrate may be a woven or non-woven textile formed from natural or synthetic components.

In yet further examples, the porous substrates may be building materials. The building materials may have functional particles provided therein to provide desirable properties such as fade resistance, fungal resistance, and mold resistance. Examples of suitable building materials include, but are not limited to, drywall, fiberboard, wood, ceiling tile, oriented strand board, medium density fiberboard, grout, cement, concrete, ceramics, graphite-containing material, carbides, porous metal, textured metal, and linoleum, or combinations thereof.

It will be understood that the substrate may be of any suitable size and shape. It will be further understood that the functional particle or particles may be provided on or in any portion or portions of the substrate. It will also be understood that the interpenetrating polymer network may be provided on or in any portion or portions of the substrate.

Any suitable functional particle may be used. For purposes of defining and describing the present invention, the term "functional particle" shall be understood as referring to a moiety that functions in any desired manner in a substrate. For example, functional particles may be nanoparticles, microparticles, or macro-sized particles. In some examples, the functional particles may be at least one nanoparticle selected from carbon nanotubes, TiO₂, Ag, carbon black, ZrO₂, MgO, SiO₂, ZnO, Al₂O₃, Nb₂O₅, WO₃, Ta₂O₅, HfO₂, SnO₂, SiAlO_{3 5}, SiTiO₄, ZrTiO₄, Al₂TiO₅, ZrW₂O₈, CaCO₃, MoO₃, Mo, V₂O₅, Sb₂O₅, Pd, ZnO, Fe₃O₄, Kaolin, Sulfur, CoFe₂O₄, Au, Pt, Cu, Ni, quantum dots, halloysites, inorganic nanomaterials, organic nanomaterials, and naturally occurring nanomaterials, and combinations thereof. It will be understood that the nanoparticles may be modified or unmodified in any suitable manner. For example, the nanomaterials may further include active ingredients. For example, nanotubules, such as halloysites, may encapsulate any suitable active ingredient (see US Patent No. 5,651 ,976). The interpenetrating polymer network may inhibit or slow down the leaching and release of such an active ingredient.

In other examples, the functional particles may be selected from activated carbon, fabric softeners, thermochromic materials, magnetic particles, reflective particles, fire retardants, fire suppressant chemicals, insect repellents, electromagnetic interference shielding materials, radio frequency interference shielding materials, heat-releasing phase change agents, fragrances, metallic reflector colloids, pigments, zeolites, dyes, fertilizers, sun blocking agents, pharmaceuticals, antimicrobial agents, anti-fungal agents, and sporicidal agents, and combinations thereof.

Functional particles such as those listed above can be unmodified or can be modified with functional groups, including but not limited to, amino-, carboxy-, and alkyl-silanes and amino-, carboxy-, and alkyl-thiols, or biochemicals such as proteins, nucleic acids, carbohydrates. In addition, the functional particles can be modified with molecular receptors, to sense outside chemical or biological compounds.

It will be understood that more than one type of functional particle may be selected to provide a substrate having desired properties. For example, silver particles may be chosen to provide an antibacterial or sporicidal effect and TiO₂ particles may be chosen to provide a sun protection effect.

The functional particle or particles may be provided in any suitable concentration. One having skill in the art will be able to select a suitable concentration depending on the type of substrate, desired application, and desired effect of the functional particle in the article.

Any suitable interpenetrating polymer network monomers may be used. A variety of interpenetrating polymer network monomers are available and known to those skilled in the art. For example, suitable interpenetrating polymer network monomers include, but are not limited to, chitosan, starches, and sugar-related monomers, and combinations thereof. In some examples, the interpenetrating polymer network monomers may be chitosan monomers.

The interpenetrating polymer network monomers are polymerized to form the interpenetrating polymer network. It will be understood that any suitable interpenetrating polymer network monomers may be used. Examples of suitable interpenetrating polymer network monomers include, but are not limited to, chitosan, starches, sugar-related monomers, lactic-cσ-glycolic acid, esters, vinyl monomers, epoxides, isocyanates, urethanes, imides, ethylenes, styrenes, ethylene oxides, amides, phenol-formaldehyde resins, and silicon monomers and combinations thereof. In some examples, the interpenetrating polymer network monomers comprise chitosan. In other examples, the interpenetrating polymer network monomers comprise starches. In yet further examples, the interpenetrating polymer network monomers comprise sugar-related monomers.

The polymerized interpenetrating polymer network monomers are intertwined/interlocked with the porous substrate. In some examples, the interpenetrating polymer network monomers contain groups that may be reactive with the substrate either before or after polymerization. In some examples, the interpenetrating polymer network may further have any suitable functional groups. For example, the interpenetrating polymer network may have functional groups such as amines, carboxylic acid, N-hydroxy succinimide, isocyanates, hydroxyl groups, and combinations thereof. These functional groups may be reactive with certain components of the substrate. For example, the functional groups may be reactive with components of natural or synthetic textiles. In other examples, functional groups may comprise biochemicals such as proteins, nucleic acids, carbohydrates. In yet further examples, the functional groups may be molecular receptors to sense outside chemical or biological compounds.

In some examples, the interpenetrating polymer networks may have reactive chemical groups on their surfaces which do not react with the surface of the functional particles, but do react with a variety of organic substrates, such as the aromatic rings in polyesters and polystyrene, amino groups in wool and leather, and the hydroxyl groups in cotton and paper. In other examples, the interpenetrating polymer networks have reactive chemical groups on their surfaces that may react with polymer substrates

The interpenetrating polymer network may function in any suitable manner to inhibit release of functional particles from the substrate. The interpenetrating polymer network may function as a physical barrier to the functional particles. For example, the interpenetrating polymer network may be intertwined with the functional particles. In some instances, active ingredients in or on the functional particles may be inhibited or slowed from releasing from the substrate by the interpenetrating polymer network.

The interpenetrating polymer networks may be present in or on the substrate in any suitable amount. For example, the interpenetrating polymer networks may comprise between about 0.1% to about 10% by weight of the treated substrate. It will be understood that one having skill in the art will be able to select a suitable amount of the interpenetrating polymer network depending on the application. Figure 1 illustrates one example of an article in accordance with embodiments of the present invention. The article is shown before and after polymerization of the interpenetrating polymer network monomers.

In accordance with further embodiments of the present invention, methods for treating articles are provided. The methods comprise providing a porous substrate having at least one functional particle and at least one interpenetrating polymer network monomer and polymerizing the at least one interpenetrating polymer network monomer such that an interpenetrating polymer network is formed and release of the at least one functional particle from the porous substrate is inhibited. The substrates, interpenetrating polymer network monomers, and functional particles may be those discussed above.

The functional particles and the interpenetrating polymer network monomers may be provided in any suitable manner in any suitable concentrations. It will be understood that solutions containing one or both of the functional particles and interpenetrating polymer network monomers may have any suitable concentrations and any suitable solvents may be used.

In some embodiments, the step of providing a porous substrate comprises treating the porous substrate simultaneously with the at least one functional particle and the at least one interpenetrating polymer network monomer. Such a method is schematically illustrated in Figure 2. It will be understood that the porous substrate may be treated in any suitable manner. For example, a solution having the at least one functional particle and the at least one interpenetrating polymer network monomer may be applied to the substrate by spin coating, dip coating, flow coating, spray coating, painting, or combinations thereof. It will be understood that the porous substrate may be treated in any suitable manner, including, but not limited to, spin coating, dip coating, flow coating, spray coating, painting, or combinations thereof.

In one example, a fungicide-impregnated halloysite is absorbed on a porous substrate by immersing the substrate in a dipping solution comprised of fungicide-impregnated halloysite/chitosan suspended in either water, hexane, dichloromethane, chloroform, tetrahydrofuran, benzene, toluene, or other organic solvent or a combination thereof. The fungicide-impregnated halloysite/chitosan solution may have a concentration of between about 0.001% and about 50% by weight. In some examples, the substrate is allowed to dry before further processing. Polymerization of the chitosan to create the interpenetrating polymer network within the porous substrate can then be initiated by heat or in any other suitable manner, such as by appropriate chemicals. In other embodiments, the step of providing a porous substrate comprises treating the porous substrate with the at least one functional particle and subsequently treating the porous substrate with the at least one interpenetrating polymer network monomer. Such a method is schematically illustrated in Figure 3. After the interpenetrating polymer network monomer is applied, polymerization may be performed in any suitable manner.

In one example, the substrate may be immersed in a dipping solution comprising functional particles suspended in water, hexane, dichloromefhane, chloroform, tetrahydrofuran, benzene, toluene, or other suitable solvents. In some examples, the functional particles may have a concentration in the dipping solution between 0.001% and 50% by weight. In some embodiments, the substrate is allowed to dry before further processing.

In another example, a fungicide-impregnated halloysite may be applied to the desired porous substrate by spraying a halloysite solution on the surface or dipping it in a halloysite solution. Next a solution of a an interpenetrating polymer network monomer, e.g. chitosan, can be applied to the substrate. Polymerization may then performed in any suitable manner. For example, the substrate may be allowed to dry in an oven above about 9O⁰C when the interpenetrating polymer network monomer is chitosan. The heat-curing process allows the chitosan monomers to react and crosslink with each other on the halloysite surface and in the porous substrate creating the interpenetrating polymer network.

The polymerization may be performed in any suitable manner. For example, the step of polymerizing may be performed by at least one of drying, heating, UV curing, condensation, radiation curing, thermally curing, and chemically curing the substrate having the interpenetrating polymer network monomer thereon. The particular polymerization step is chosen to be performed in a manner and for an amount of time sufficient to allow crosslinking of the interpenetrating polymer networks monomers to any desired extent. It will be understood that the interpenetrating polymer network monomers have reactive groups that may not react with the porous substrate but that react with each other to crosslink.

In some examples, the polymerization method avoids some wet chemical processes that may have a deleterious effect on functional particles. In other examples, the methods may prevent the functional particles from being adversely effected or reacted, such that the functional particles may maintain their function in the treated article.

In embodiments of the present invention, functional particles on substrates may have preserved or even enhanced their functions. In addition, functional particles and active ingredients associated with or in the functional particles may be inhibited from being released from the substrates. This may allow the substrates to be used for longer periods of time or with increased efficacy over untreated substrates. It will be understood that the articles may be used for any suitable purpose. For example, the articles may be applicable to many medical, electronic, agricultural, military, industrial, building materials, water purification and aerospace related applications. Some examples would include, but are not limited to, wound dressings with encapsulated antibiotic halloysite or plain halloysite for blood absorption, electronic shielding materials, water and air filtration, air freshening and deodorizer mediums, pheromone and repellant applications, personal protective masks and garments for military use. It is understood that these examples only illustrate some of the potential uses for the treated articles and methods of treating articles.

The present invention will be better understood by reference to the following examples which are offered by way of illustration and not limitation.

EXAMPLES Example 1 : Stabilized hallovsite nanotube in textile composites

Halloysites are naturally occurring nanomaterials. They are hollow tubes with diameters that may be smaller than 100 nm, with lengths that may range from about 500 ran to over 1.0 microns. Halloysites are composed of aluminum, silicon, hydrogen, and oxygen and are formed naturally in the earth by surface weathering of aluminosilicate minerals.

Textiles (68% polyester, 32% cotton) were cut into small pieces (2.5 cm x 2.5 cm). The textile piece was placed in a suspension of 20 mg of halloysites in 20 ml of hexane, followed by sonication at room temperature for 5 min to form the textile-halloysite composite. After drying the textile in a vacuum oven at 25 ⁰C for 12 hours, it was dipped in a solution of 1% chitosan aqueous solution for 1 min. The coated textile was then dried and heat-cured in a vacuum oven at 100⁰C for 12 hrs. To test for stability, both a textile/halloysite composite stabilized / immobilized on the textile substrate by chitosan IPN and an unstabilized textile/halloysite as a control were placed in 20 ml of water, and sonicated for 10 min. As seen in Figure 4., the IPN treated surfaces prevented the release of halloysite nanotubes from the surface, whereas the non-IPN treated and non-crosslinked materials had a release of substantial amounts of halloysite material. Additional tests using chitosan solutions containing halloysite that were sprayed onto the textile or cellulose filter papers showed similar results when washed and sonicated. Example 2: Stabilized carbon black nanoparticles in textiles

Activated carbon itself or carbon beads are the main active component in wound dressings and in military garments for decontamination of chemical warfare agents (CWA), because they can absorb substantial amounts of toxins, volatile organic chemicals and their vapors. Despite the superior absorption capacity of activated carbon, options for effective use of the material are limited because carbon is basically an inert material and it is difficult to chemically modify the surface. Without chemical bonding between the activated carbon and textile, textile/activated carbon composites tend to release activated carbon over time, which can lead to skin irritation, skin darkening and respiratory problems. Methods for the stabilization of activated carbon particles in textiles are therefore of considerable interest.

In this example, a textile sample (68% polyester, 32% cotton) was cut into small pieces (2.5 cm x 2.5 cm). The textile pieces were placed in a suspension of 20 mg of carbon black (Darco® G-60, -100 mesh, Aldrich) in 20 ml of hexane, and sonicated at room temperature for 5 min to form a textile/carbon black composite. After drying the textile in a vacuum oven at 25 ⁰C for 12 hours, it was dipped in a solution of 1% chitosan aqueous solution for 1 min. The coated textile was then dried and heat-cured in a vacuum oven at 100⁰C for 12 hrs. To test for stability, both a textile/carbon black composite stabilized by chitosan IPN and an uncured, unstabilized textile/carbon black as a control were placed in 20 ml of water, and sonicated for 10 min to generate washing conditions likely to cause the release of carbon black from the textiles. In addition, chitosan solutions containing carbon black were sprayed onto the textile or cellulose filter papers. All of the activated carbon treated surfaces using chitosan IPN cured and stabilized treatments showed minimal or no release of activated carbon from the surfaces. In contrast, activated carbon surfaces that were not treated with chitosan IPN showed significant release of activated carbon into the washing/sonication solution.

Example 3. Textiles with stabilized silver nanoparticles

Textile swatches (68% polyester, 32% cotton) were cut into small pieces (2.5 cm x 2.5 cm). The textile pieces were placed in a suspension of 20 mg of silver nanoparticles (NanoDynamics S2-80 Ag nanoparticles) in 20 ml of hexane, followed by sonication at room temperature for 5 min to form the textile- Ag composite. After drying the textile in a vacuum oven at 25 ⁰C for 12 hours, it was dipped in a solution of 1% chitosan aqueous solution for 1 min. The coated textile was then dried and heat-cured in a vacuum oven at 100⁰C for 12 hrs. To test for stability, both a textile/ Ag composite stabilized / immobilized by chitosan IPN and an unstabilized / unimmobilized textile/ Ag as a control were placed in 20 ml of water, and sonicated for 10 min to generate washing conditions likely to cause the release of Ag from the textiles. The chitosan-treated textiles performed better than those the untreated controls, as seen in Figure 4. In addition, chitosan solutions containing silver nanoparticles were sprayed onto the textile or cellulose filter papers and were found to significantly inhibit the release of nanosilver into the washing/sonication solutions in contrast to the controls.

Example 4: Preparation and testing of stabilized TiO? nanoparticles-textiles.

Degussa P25 TiO₂ nanoparticles are approximately 21 nm in diameter and very hydrophilic due to the hydrolyzed TiO₂ surface. Because of the hydrophilic nature of these TiO₂ nanoparticles, retaining them in a textile against a water wash is difficult, even more so than retaining carbon black.

A small textile piece (2.5 cm x 2.5 cm) was placed in a suspension of 20 mg of TiO₂ in 20 ml of hexane, followed by sonication at room temperature for 5 min to form a textile/TiO₂ composite. After drying the textile in a vacuum oven at 25 ⁰C for 12 h, it was dipped in a solution of 1% chitosan aqueous solution for 1 min. The coated textile was then dried and heat-cured in a vacuum oven at 100⁰C for 12 hours. To test for stability, both a textile/TiO₂ composite stabilized / immobilized by chitosan IPN and an unstabilized textile/ TiO₂ as a control were placed in 20 ml of water, and sonicated for 10 min to simulate washing conditions likely to cause the release of TiO₂ from the textiles. In other experiments, chitosan solutions containing TiO₂ nanoparticles were sprayed onto the textile or cellulose filter papers. We observed minimal or no release of TiO₂ nanoparticles from the IPN treated textiles or filter papers upon washing/sonitation.

Example 5: Stabilized carbon nanotube in textile composites

Textiles (68% polyester, 32% cotton) were cut into small pieces (2.5 cm x 2.5 cm). The textile piece was placed in a solution of 20 mg of carbon nano tubes in 20 ml of toluene, followed by sonication at room temperature for 60 min to make textile-carbon nanotube composite. After drying the textile in a vacuum oven at 25 ⁰C for 12 h, it was dipped in a solution of 1% chitosan aqueous solution for 1 min. The coated textile was then dried and heat-cured in a vacuum oven at 100⁰C for 12 hrs. To test for stability, both a textile/carbon nanotube stabilized / immobilized by chitosan IPN and an unstabilized textile/carbon nano tubes as a control were placed in 20 ml of water, and sonicated for 10 min to generate washing conditions likely to cause the release of carbon nanotubes from the textiles, hi addition, chitosan solution containing carbon nanotubes were sprayed onto the textile or cellulose filter papers. Minimal or no release of carbon nanotubes from washing/sonitation were observed for the chitosan IPN treated samples.

Example 6: MDF and stabilized halloysites

3-iodo-2-propynyl-iV-butylcarbamate (IPBC) is a widely acceptable fungicide that has been registered with the EPA since 1974. In this example, 20 weight percent of IPBC was impregnated in halloysite. Medium-density fiberboard (MDF) was cut into 0.5 x 0.5 x 0.25 inch squares. A stock solution of 0.5g of 11.8% chitosan gel was added to a 2OmL vial, and then 5mL of de-ionized water was added to the vial. The vial was placed into a shaker at 300rpms for 2 min. 3.94g of IPBC-impregnated halloysite was added to the chitosan aqueous solution followed by shaking at 300 rpm for 1 min. 143.75g of the solution was coated on the surface of each MDF square. The MDF squares were dried in an oven for 3 hours at 90^°C, to form IPN.

In control experiments, MDF squares were also coated with a commercially available fungicide, Fungitrol 720 (available from ISP). Fungitrol 720 is a fungicide, which contains 20% rPBC by weight. Fungitrol is composed of 20% of PBC dissolved in 80% polyethylene glycol. For the MDF coated with Fungitrol, 60mg of Fungitrol 720 was coated on the surface of each MDF square followed by air drying.

A test method was developed for evaluating the slow release of encapsulants (IPBC in this case) from halloysite tubes, during aggressive washing with water. The following procedure was used. The MDF samples were placed at the bottom of separate 600 ml beakers. Then 500 ml of water was added to each beaker. The beakers were placed on a shaking plate in order to obtain continuous swirling of the water around the MDF samples. Each day, 500 ml of water was decanted from the halloysite sample, and replaced with fresh water up to the 500 ml mark on the beaker. Every other day one sample was air dried and subject to the zone of inhibition test described below. This process was repeated until all samples were collected.

After all the samples were collected, the dry MDF samples were placed on the surface of potato dextrose agar (PDA) inside Petri dishes inoculated with Aspergillus niger spores. After 2 days of incubation, the diameter around the sample where mold growth was not observed was measured. This area is termed the zone of inhibition (ZOI). The MDF samples released IPBC after up to 4-days of aggressive washing. The IPBC-impregnated halloysite coating layer was stable during the washing condition, showing stable formation of interpenetrating polymer networks.

Figure 5 shows the zone of inhibition of MDF coated with fungicide-impregnated halloysite and Fungitrol 720 from ISP. As seen in the Figure 5, BPBC-impregnated halloysite does not have burst effect, showing sustained slow release of biocide IPBC from halloysite that are coated on MDF. However, Fungitrol-coated MDF has a burst effect because Funtitrol 720 is not a slow release concept-based product. This data indicates that IPBC in the presence of an interpenetrating polymer network can have an extended fungicidal efficacy.

The present invention should not be considered limited to the specific examples described above, but rather should be understood to cover all aspects of the invention. Various modifications, equivalent processes, as well as numerous structures and devices to which the present invention may be applicable will be readily apparent to those of skill in the art.

Claims

1. An article, comprising a porous substrate having at least one functional particle and an interpenetrating polymer network formed with the substrate, wherein the interpenetrating polymer network comprises at least one interpenetrating polymer network monomer polymerized in the presence of the substrate to form the interpenetrating polymer network with the substrate, and wherein the interpenetrating polymer network inhibits release of the at least one functional particle from the substrate.

2. The article as claimed in claim 1 wherein the at least one functional particle comprises at least one nanoparticle comprising modified or unmodified carbon nanotubes, TiO₂, Ag, carbon black, ZrO₂, MgO, SiO₂, ZnO, Al₂O₃, Nb₂O₅, WO₃, Ta₂O₅, HfO₂, SnO₂, SiAlO_{3 5}, SiTiO₄, ZrTiO₄, Al₂TiO₅, ZrW₂O₈, CaCO₃, MoO₃, Mo, V₂O₅, Sb₂O₅, Pd, ZnO, Fe₃O₄, Kaolin, Sulfur, CoFe₂O₄, Au, Pt, Cu, Ni, quantum dots, halloysites, inorganic nanomaterials, organic nanomaterials, and naturally occurring nanomaterials, or combinations thereof.

3. The article as claimed in claim 1 wherein the at least one functional particle comprises at least one of a modified or unmodified halloysite.

4. The article as claimed in claim 1 wherein the at least one functional particle comprises activated carbon, fabric softeners, thermochromic materials, magnetic particles, reflective particles, fire retardants, fire suppressant chemicals, insect repellents, electromagnetic interference shielding materials, radio frequency interference shielding materials, heat- releasing phase change agents, fragrances, metallic reflector colloids, pigments, zeolites, dyes, fertilizers, sun blocking agents, pharmaceuticals, antimicrobial agents, anti-fungal agents, and sporicidal agents, or combinations thereof.

5. The article as claimed in claim 1 wherein the at least one interpenetrating polymer network monomer comprises chitosan, starches, sugar-related monomers, lactic-cσ-glycolic acid, esters, vinyl monomers, epoxides, isocyanates, urethanes, imides, ethylenes, styrenes, ethylene oxides, amides, phenol-formaldehyde resins, and silicon monomers and combinations thereof.

6. The article as claimed in claim 1 wherein the at least one interpenetrating polymer network monomer comprises chitosan.

7. The article as claimed in claim 1 wherein the at least one interpenetrating polymer network monomer comprises a starch.

The article as claimed in claim 1 wherein the at least one interpenetrating polymer network monomer comprises a sugar related monomer.

8. The article as claimed in claim 1 wherein the at least one interpenetrating polymer network contains at least one group that is reactive with the porous substrate.

9. The article as claimed in claim 1 wherein the porous substrate is selected from fibers, yarns, porous textiles, carpeting, retractable awnings, outdoor fabrics, polymeric surfaces and porous membranes, or combinations thereof.

10. The article as claimed in claim 1 wherein the porous substrate is selected from building materials, drywall, fϊberboard, wood, ceiling tile, oriented strand board, medium density fiberboard, grout, cement, concrete, ceramics, graphite-containing material, carbides, porous metal, textured metal, and linoleum, or combinations thereof.

11. The article as claimed in claim 1 wherein the interpenetrating polymer network monomer is chitosan and wherein the functional particle is at least one of a modified or unmodified halloysite.

12. The article as claimed in claim 1 wherein the interpenetrating polymer network is intertwined with at least some of the functional particles.

13. The article as claimed in claim 1 wherein the interpenetrating polymer network comprises between about 0.1% to about 10% by weight of the article.

14. A method for treating articles, comprising: providing a porous substrate, at least one functional particle, and at least one interpenetrating polymer network monomer; and polymerizing the at least one interpenetrating polymer network monomer such that an interpenetrating polymer network is formed whereby release of the at least one functional particle from the porous substrate is inhibited.

15. The method as claimed in claim 14 wherein the step of providing a porous substrate comprises treating the porous substrate with the at least one functional particle and subsequently treating the porous substrate with the at least one interpenetrating polymer network monomer.

16. The method as claimed in claim 15 wherein the treating the porous substrate is performed by spin coating, dip coating, flow coating, spray coating, painting, or combinations thereof.

17. The method as claimed in claim 14 wherein the step of providing a porous substrate comprises treating the porous substrate simultaneously with the at least one functional particle and the at least one interpenetrating polymer network monomer.

18. The method as claimed in claim 14 wherein the step of polymerizing is performed by at least one of drying, heating, UV curing, radiation curing, condensation, thermally curing, and chemically curing.