RU2736617C2 - Metamaterial, production and use - Google Patents

Abstract

FIELD: nanotechnology.

SUBSTANCE: invention can be used in production of lubricants, protective screens, electric current leads. First, preparing a surface for gripping graphene by distributing a mixture of N, N-dimethylformamide and tetrahydrofuran in volume ratio of 1:1 to 3:1 on the inner surface of the container, heating for 7–9 hours to 400–500 °C and subsequent cooling to 25–30 °C. Container is made from heat-resistant and chemically neutral material, for example, borosilicate glass containing at least 80 % SiO₂ and at least 13 % B₂O₃. Then one prepares a liquid mixture containing 1–15 mg of graphene flakes per 1 ml of perfluorotributylamine. Obtained mixture is distributed along inner surface of container, inner surface of container is cooled to minus 32–50 °C, is subjected to magnetic field intensity of 0.5–2.5 T for 12–24 hours, obtained liquid metamaterial is heated to 20–25 °C. Obtained metamaterial is a two-level regular grid with cell size from 15 to 25 nm, consists of perfluorotributylamine and graphene nanoparticles distributed in it and can be mixed and/or hardened in fine ceramics, plastics, alloys, solid-state polymers, liquid and amorphous substances.

EFFECT: higher efficiency of the process of producing metamaterial having high dispersibility in perfluorocarbon solvents.

3 cl, 3 dwg

Description

The invention relates generally to metamaterials, more specifically, the invention relates to the composition of a metamaterial, a method for its production and its practical application.

The present invention, in particular, relates to dispersion solutions of graphene, a method for preparing such solutions, as well as the use of such graphene solutions. The possibility of obtaining graphene for practical solutions is of great interest from the point of view of industrial applications, in particular, with regard to the suitability of these solutions for a specific application. In particular, such solutions can be easily used for the deposition of graphene nanoparticles, flakes or nanotubes in this carrier.

In the following description, references between square brackets ([]) refer to the list of references following the examples.

Carbon is known to have four unique crystal structures or structures: diamond, graphite, fullerenes, and a recently described family of structures including two-dimensional carbon flakes, nanoparticles and nanotubes known as the "graphene family." Graphene or the base plane of graphite, which has long been considered a virtual object, has recently become a reality thanks to the work of Novoselov et al. ((KS Novoselov, A.K. Geim, SV Morozov, D. Jiang, Y. Zhang, SV Dubonos, IV Grigorieva, and AA Firsov, "Electric field effect in atomically thin carbon films", Science, 306, 666-669 (2004) [1]; KS Novoselov, AK Geim, SV Morozov, D. Jiang, MI, Katsnelson, IV Grigorieva , SV Dubonos, AA Firsov, "Two-dimensional gas of massless Dirac fermions in graphene", Nature, 438, 197-200 (2005) [2], which describe the electronic properties of this singular object. It is known that graphite leads to the formation intercalating compounds (graphite intercalation compounds or GICs) with either electron donors or acceptors ("Synthesis of graphite intercalation compounds", A. Herold in Chemical physics of intercalation, AP Legrand and S. Flandrois Eds, NATO ASI Series, series B, Vol. 172, pp. 345 (1987 [3]). Terna pry compounds having the formula (THF) C 24 have been obtained as early as 1965 by reduction of graphite with a polyaromatic alkaline salt of the molecule in THE. (C, Stein, J. Poulenard, L. Bonnetain, J. Gole, C. R. Acad. Sci. Paris 260, 4503 (1965) [4]).

The unique properties of graphene, confirmed by scientific experiments, have led to numerous research activities aimed at the practical application of this new structure and the development of methods for the full-scale production of graphene-based composite materials.

Since 2004 and the publication of Novesolov et al., The World of Physics has shown great interest in the electronic properties of the isolated plane of graphene or graphite (Electric field effect in atomically thin carbon films, Novoselov et al. Science 306, 666 (2004)) [5]) ... The method of exfoliating the cut by Novoselov et al. Allows obtaining only a few isolated planes. In addition, such planes are stabilized on the surface, which prevents their subsequent processing, for example, for their integration into the matrix. However, there is currently no effective way to solubilize graphene, and graphene solutions as such have remained illusory so far. However, a number of fairly promising approaches have recently been described. Several attempts have been reported to solubilize graphene, mainly through functionalization of graphite (Chakraborty et al., "Functionalization of potassium graphite", Angew. Chem, Int. Ed., 46, 4486-4488 (2007) [6]) or by functionalization ( Niyogi, S .; Bekyarova, E .; Itkis, ME; McWilliams, JL; Hamon, MA; Haddon, RC, "Solution Properties of Graphite and Graphene", J. Am, Chem, Soc, 128, 7720-7721 (2006 ) [7], Mc Allister, MJ; Li, JL; Adamson, DH; Schniepp, HC; Abdala, AA; Liu, J .; HerreraAlonso, M .; Millius, DL; Car, R .; Prud'homme, RK ; Aksay, IA, "Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite", Chem. Mater., 2007; ASAP Article [8]).

Among the most promising approaches, we should mention US patent 9120675 [9], which describes a method for solubilizing graphene and its application, including the production of composites. The method according to the invention is characterized in that it comprises the following steps carried out in an inert atmosphere:

- reduction of graphene with an alkali metal with the formation of a graphene intercalation compound and

- the effect of a graphite intercalation compound on a polar aprotic solvent to lead to reduction of the graphene solution. The invention relates, in particular, to graphene solutions and graphene flakes (planes) obtained using this method, as well as to the use of such graphene solutions and flakes. The main disadvantage of the above method is that it is not able to provide a uniform distribution of graphene on the surface, taking into account the high hydrophobic properties of graphene.

Several other attempts to solubilize graphene have been reported, mainly due to functionalization of graphite (Chakraborty et al., "Functionalization of potassium graphite", Angew. Chem, Int. Ed., 46, 4486-4488 (2007) [10] or by functionalization of graphite oxide. (Niyogi, S .; Bekyarova, E .; Itkis, ME; McWilliams, JL; Hamon, MA; Haddon, RC, "Solution Properties of Graphite and Graphene", J. Am, Chem, Soc, 128, 7720 -7721 (2006) [11]; Mc Allister, MJ; Li, JL; Adamson, DH; Schniepp, HC; Abdala, AA; Liu, J .; Herrera Alonso, M .; Millius, DL; Car, R .; Prud'homme, RK; Aksay, IA, "Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite", Chem. Mater., 2007; ASAP Article [12]).

However, one of the disadvantages of such methods is that the resulting graphene flakes are not fully functionalized and separated.

Thus, there is an urgent need for methods of graphene solubilization that eliminate these problems and obstacles, as well as the search for a method that makes it possible to obtain graphene materials while minimizing production costs.

A method for improving the industrial availability of graphene in large quantities is described in US patent 9134940 [13], which claims a method for producing nanoscale graphene flakes, which includes the stages of applying a graphene material in contact with molecular or atomic oxygen or a substance capable of releasing molecular or atomic oxygen, obtaining a precursor consisting of oxygen functionalized graphene material (OGF) having a molar ratio of carbon to oxygen above 8: 1; subsequently, by reducing (chemically or physically) said FOG precursor, to obtain nanoscale graphene flakes characterized by a carbon / oxygen molar ratio above 20: 1. The main disadvantage of this method is that rather large "oxide frames" cause discrete functional properties of such raw materials ...

The recently discovered properties of graphene make this structure promising for use in composite materials. Existing advanced composites used, for example, in aerospace structures and aircraft applications, do not meet the performance requirements of these and other applications. Accordingly, there is a need for reinforced composites having improved mechanical properties such as higher tensile strength, strain to fracture, fracture toughness, durability, impact resistance, abrasion resistance, damping, and other advantages. There is also a need for methods of making such improved materials.

The practical application of graphene for the production of composite metamaterials is described in US patent 9 120 908 [14]. The patent claims reinforced resin compositions based on nanomaterials and related methods. The compositions include a reinforcing material such as graphene, polyamic acid, carbon nanotubes, or dimethylacetamide, which is dispersed in the resin. The reinforcing material is present in the resin from about 0.001 to about 10 wt. %. Methods for making these compositions and methods for adjusting the composition to achieve a specific set of mechanical properties are also provided.

However, the scope of application of resins made in accordance with [14] is very limited, therefore, there is a need for composite metamaterials with a wider range of applications.

The same is true for the thermoplastic resin described in US patent 9123889 [15], where the resin is fortified with a prefabricated dispersion of nanotubes. However, a method for producing such a dispersion is not disclosed.

Another US patent 9,159,463 [16] describes a conductive material that includes a carbon material and a metal material mixed with and / or laminated with a carbon material. The carbonaceous substance has at least one dimension of 200 nm or less. The carbonaceous substance includes graphene selected from single-layer graphene and multilayer graphene, part of the carbon atoms making up graphene is replaced by a nitrogen atom. The metallic substance includes at least one of metallic particles and a metallic wire. A conductive material where I.sub.401.2 representing the intensity at 401.2 eV is higher than I.sub.398.5 representing the intensity at 398.5 eV in the X-ray photoelectron spectrum with 1 s electron from the nitrogen atom. Compared to this, the claimed invention offers a much higher productivity, namely, it operates at 600 MeV, and the material does not contain any metal particles.

The present invention has been made in view of the above-described problems for conventional techniques, and solves the problem of providing a nanocomposite capable of being highly dispersible in a liquid cocktail comprising a perfluorocarbon solvent and a dispersion containing the nanocomposite. In particular, the nanocomposite obtained in accordance with the present invention comprises graphene-based nanostructure, where graphene nanoparticles, platelets or nanotubes are evenly distributed in perfluorotributylamine, forming a two-level regular grid with a cell size ranging from 15 to 25 nm.

The method for obtaining the considered metamaterial includes the following stages:

- surface preparation for graphene capture using

• distribution of a mixture of N, N-dimethylformamide and tetrahydrofuran in the range from 1: 1 to 3: 1 (v / v) over the inner surface of a container made of a heat-resistant and chemically neutral substance. The experiments used borosilicate glass with a content of at least 80% SiO ₂ and a content of B ₂ O ₃ of at least 13%. Other materials with similar properties can be used, eg fine ceramics;

• heating the inner surface for 7-9 hours at a temperature of plus 400 degrees Celsius to plus 500 degrees Celsius;

• cooling of the thus coated inner surface of the container to a temperature range of plus 25-30 degrees Celsius;

- preparation of substructural fluid by mixing perfluorotributylamine with graphene flakes, particles or nanotubes in the range from 1 to 15 mg of graphene per 1 ml of perfluorotributylamine;

- distribution of substructural fluid over the inner surface of the container;

- cooling the inner surface of the container to a temperature of minus 32-50 degrees Celsius;

- application of a magnetic field with an intensity of 0.5-2.5 T into a container for 12-24 hours;

- heating the obtained liquid metamaterial to a temperature range of plus 20-25 degrees Celsius.

The resulting substance was found to be capable of high dispersibility in various materials. In addition, the introduction of the substance under consideration into various materials, such as, for example, composites, ceramics, plastics, alloys, solid polymers, and other liquid and amorphous substances, allows the graphene particles to be evenly distributed inside the material, forming a continuous graphene network. Thus, the material acquires the features of a metamaterial.

Due to the special properties of the metamaterial in question, a number of practical applications are described, although the list is not exhaustive. One of the properties of the claimed metamaterial makes it especially interesting for various industries, namely, the ability to mix and cure in ceramics, plastics, alloys, solid polymers, composites and other liquid, solid and amorphous substances.

Among the most promising are the use of the claimed metamaterial for the following purposes:

- Using a metamaterial as an electrical conductor with a resistance range from 0.0002 Ohm / cm ² to 0.000001 at a temperature range from minus 173 degrees Celsius to plus 102 degrees Celsius. Experiments (see Example 6 above in this description) have provided a solid basis for this statement.

- Using metamaterial as a shield against radiation and electromagnetic waves due to the ability to significantly absorb and / or reflect radiation in the frequency range from 30 MHz to 30 EHz.

Experiments (see claim 5 and FIGS. 1-5 later in this specification) provided a solid basis for such a claim.

- The use of a metamaterial as a lubricant capable of maintaining lubricating properties in the temperature range from minus 180 degrees Celsius to plus 700 degrees Celsius. Corresponding experiments are described in example 4 of the claims, which presents the results of tests of thin-layer grease under extreme temperature conditions.

To provide a better understanding of the claimed invention, the following drawings are provided:

FIG. 1 - Radiation shock test:

1.1- Before testing. Microchips are disabled.

1.2 - Before testing. Microchips are included.

1.3 - X-ray source. Before irradiation.

1.4 - X-ray source. After irradiation.

It can be seen that the control chip (left) is not working.

1.5 - Spontaneous process of rebooting the control microcircuit (left).

FIG. 2 - Checking the lubricating properties of the metamaterial:

2.1 - Spacesuit with shoulder sleeve lubrication.

2.2 - Scheme of the dependence of the viscosity of the lubricant on temperature.

FIG. 3 - Conductivity test:

3.1 - Electrical diagrams (R - test lead).

3.2 - Electrical diagrams (X - metamaterial).

3.3 - Diagram of resistance / temperature dependence.

Example for claim 4. Lubrication of a thin layer in extreme temperature conditions.

The metamaterial according to claim 1 and, alternatively, according to claim 2, was tested on the movable component (shoulder sleeve) of a standard spacesuit (see Fig. 2.1) subjected to a burst test of 8 bar (0.79 MPa). The sliding ability of the two coated surfaces has increased 5 times. Wear resistance increased 9.5 times per 100,000 cycles (versus 47,000 laboratory test cycles described in Advanced Functional Materials, Volume 24, Issue 42, pages 6640-6646, November 12, 2014 [17]). The lubricant used in the ball segment of the suit has shown a 15-fold increase in segment performance. The same results were also recorded at temperatures of minus 180 degrees Celsius and plus 700 degrees Celsius (see Fig. 2.2).

Example for item. 5. Radiation protection

Below is an example of the practical use of the claimed metamaterial as a shield against a high dose of X-ray radiation (see Fig. 1). The experimental and control microcircuits contained one processor with a random number algorithm, a controller and lamps for visualization. The experimental chip was flooded with the declared metamaterial (see item 1 of the formula). The chips are not protected by any special varnish. During irradiation with an X-ray device, the microcircuits were switched on and intensely shaken on the vibration platform. The test was carried out in two stages at 30 Gray and 60 minutes each. After the first stage of control, the chip performed a spontaneous reboot. After the 2nd stage, such a reboot began to repeat every 20-30 minutes. It should be noted that Toshiba robots with US protected microcircuits, which are currently used by TEPCO, also began to reboot spontaneously and fail after working for 4 hours at a dose of 26 Gray.

Example for claim 6. Conductivity tests

For the experiments (see Fig. 3), a simple circuit was installed containing an R-copper wire, an X-metamaterial according to item 1 and a power source. For measurements, a Kelvin bridge or similar device can be used. The copper wire showed resistance in the range of 0.017 to 0.018 ohm / cm ² at average room temperature. Then the copper wire was replaced with a sample made of metamaterial according to claim 1 of the formula. Records in this case indicated a recorded range of 0.0002 Ohm / cm ² to 0.000001 Ohm / cm ² at the same room temperature. The experiments were carried out in a wide range of temperatures, namely in the range from minus 173 degrees Celsius to plus 102 degrees Celsius. The diagram shown in FIG. 3.3, shows the temperature / resistance dependence. The same results were obtained using the metamaterial under item 2.

Claims (12)

1. Metamaterial consisting of perfluorotributylamine and graphene nanoparticles in the form of flakes, where the flakes are evenly distributed in perfluorotributylamine, forming a two-level regular network with a cell size in the range from 15 to 25 nm. 2. The metamaterial according to claim 1, mixed and / or cured in fine ceramics, plastics, alloys, solid polymers, liquid and amorphous substances. 3. A method for producing a metamaterial according to claim 1, which includes the steps: - prepare the surface to capture graphene using • distribution of a mixture of N, N-dimethylformamide and tetrahydrofuran in a ratio of 1: 1 to 3: 1 (v / v) over the inner surface of a container made of a heat-resistant and chemically neutral material such as, but not exclusively, borosilicate glass with content of at least 80% SiO ₂ , and with a content of B ₂ O ₃ at least 13%; • heating the inner surface for 7-9 hours at a temperature of plus 400-500 ° C; • cooling of the thus coated inner surface of the container to the temperature range of plus 25-30 ° С; - prepare a liquid mixture of perfluorotributylamine with graphene flakes in the range of 1-15 mg of graphene per 1 ml of perfluorotributylamine; - distribute the thus obtained liquid mixture over the inner surface of the container; - cool the inner surface of the container to a temperature of minus 32-50 ° C; - exposed to a magnetic field with an intensity of 0.5-2.5 T per container for 12-24 hours; - the resulting liquid metamaterial is heated to a temperature range of plus 20-25 ° C.

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