The invention relates generally to metamaterials, more particularly, the invention relates to the composition of a metamaterial, the method of producing same and the practical applications thereof.

The present invention more particularly relates to graphene dispersive solutions, the method of producing such solutions, as well as uses of such graphene solutions. Being able to obtain graphene in the form of solutions is of a great interest from an industrial application point of view, more particularly with respect to processing these solutions for a given application. Specifically, such solutions can readily be used to deposit graphene nanoparticles, platelets or nanotubes in a given carrier.

In the description that follows, the references between square brackets ([ ]) refer to the list of references given after the examples.

Carbon is known as having four unique crystalline structures or structure families: diamond, graphite, fullerenes and the recently described structure family comprising 2D carbon platelets, nanoparticles and nanotubes, known as "graphene family". Graphene, or graphite's basic plane, which has long been considered as a virtual object, recently became a reality thanks to the work of Novoselov et al. (K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, Y. Zhang, S. V. Dubonos, I. V. Grigorieva, and A. A. Firsov, "Electric field effect in atomically thin carbon films", Science, 306, 666-669 (2004) [1]; K. S. Novoselov, A. K. Geim, S. V. Morozov, D. Jiang, M. I, Katsnelson, I. V. Grigorieva, S. V. Dubonos, A. A. Firsov, "Two-dimensional gas of massless Dirac fermions in graphene", Nature, 438, 197-200 (2005) [2] which describe electronic properties of this singular object. Graphite is known for leading to intercalation compounds (graphite intercalation compounds or GIC) with either electron donors or acceptors. ("Synthesis of graphite intercalation compounds", A. Herold in Chemical physics of intercalation, A. P. Legrand and S. Flandrois Eds, NATO ASI Series, series B, Vol. 172, pp. 345 (1987) [3]). Ternary compounds having the formula (THF)C.sub.24 have been obtained as early as 1965 by reduction of graphite with a polyaromatic molecule alkali salt 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, gave raise to numerous research works aimed at practical application of this new structure and at development of methods of full-scale production of graphene-based composite materials.

Since 2004 and the publication of Novesolov et al., the world of physics has taken a keen interest in the electronic properties of graphene or graphite isolated plane (Electric field effect in atomically thin carbon films, Novoselov et al. Science 306, 666 (2004) [5]). Novoselov et al.'s shear exfoliation method only allows obtaining a few isolated planes. In addition, such planes are stabilized on a surface, which prevents them from being subsequently handled, for example for integrating them into a matrix. However, at present, no efficient graphite solubilizing method exists, and graphene solutions as such have thus far remained elusive.

However, a number of rather prospective approaches were described recently. A few attempts to solubilize graphite have been reported, mainly by graphite flinctionalization (Chakraborty et al., "Functionahzation of potassium graphite", Angew. Chem, Int. Ed., 46, 4486-4488 (2007) [6] or by functionahzation of graphite oxide. (Niyogi, S.; Bekyarova, E.; Itkis, M. E.; McWilliams, J. L.; Hamon, M. A.; Haddon, R. C, "Solution Properties of Graphite and Graphene", J. Am, Chem, Soc, 128, 7720-7721 (2006) [7]; Mc Allister, M. J.; Li, J.L. ; Adamson, D. H.; Schniepp, H. C; Abdala, A. A.; Liu, J.; HerreraAlonso, M.; Millius, D. L.; Car, R.; Prud'homme, R. K.; Aksay, I. A., "Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite", Chem. Mater., 2007; ASAP Article [8]). Among the most prospective approaches one should mention the US patent 9120675 [9], which describes a method of solubilizing graphite and applications thereof, including the manufacture of composites and the purification of graphene. The method of the invention is characterized in that it comprises the following steps carried out under inert atmosphere:

- reduction of graphite by an alkali metal to lead to a graphite intercalation compound; and

- exposure of the graphite intercalation compound to a polar aprotic solvent to lead to a reduced graphene solution. The invention relates more particularly to graphene solutions and graphene planes obtained through said method, as well as uses of such graphene solutions and planes. The main drawback of the above method consists in that it is not capable of providing the even smooth distribution of graphene on the surface in view of the graphene high hydrophobic properties

A few other attempts to solubilize graphite have been reported, mainly by graphite functionalization (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, M. E.; McWilliams, J. L.; Hamon, M. A.; Haddon, R. C, "Solution Properties of Graphite and Graphene", J. Am, Chem, Soc, 128, 7720-7721 (2006) [1 1]; Mc Allister, M. J.; Li, J.L. ; Adamson, D. H.; Schniepp, H. C; Abdala, A. A.; Liu, J.; Herrera Alonso, M.; Millius, D. L.; Car, R.; Prud'homme, R. K.; Aksay, I. A., "Single Sheet Functionalized Graphene by Oxidation and Thermal Expansion of Graphite", Chem. Mater., 2007; ASAP Article [12]).

However, one drawback of such methods is that the resulting graphite planes are not totally functionalized and denatured.

Thus, there exists a real need for methods for solubilizing graphite that remedy these problems, drawbacks and obstacles known in the art, more particularly a method allowing to obtain graphene solutions that can readily be used for processing graphene for a given application, reducing the composite material manufacturing costs and improving accessibility to graphene in large quantity with high purity.

A way to improving accessibility to graphene in large quantity is described in the US patent 9,139,440 [13], which claims a process for the production of nanoscaled graphene platelets which comprises the steps of putting a graphite material in contact with molecular or atomic oxygen or a substance capable of releasing molecular or atomic oxygen, obtaining a precursor consisting of graphite material functionalized with oxygen groups (FOG), characterized by a carbon/oxygen molar ratio higher than 8: 1 ; subsequently, reducing (chemically or physically) said FOG precursor obtaining nanoscaled graphene platelets characterized by a carbon/oxygen molar ratio higher than 20: 1. The main drawback of this method consists in that rather big "oxide frames" cause the discrete functional properties of such raw materials

The newly discovered properties of graphene make this structure highly prospective for use in composite materials. Existing advanced composite materials used in, for example, aerospace structures and aeronautical applications do not satisfy the performance demands of those and other applications. Accordingly, there is a need for reinforced composite materials having improved mechanical properties, such as higher ultimate strength, strain-to-failure, fracture toughness, fatigue life, impact resistance, damage tolerance, damping and other advantages. There is also a related need for methods of fabricating such improved materials.

The practical application of graphene for production of composite metamaterials is described in the US patent 9,120,908 [14]. The patent claims nanomaterial reinforced resin compositions and related methods. The compositions include a reinforcing material, such as graphene, polyamic acid, carbon nanotubes, or dimethylacetamide that is dispersed into a resin. The reinforcing material is present in the resin at from about 0.001 to about 10 wt %. Also provided are methods of fabricating these compositions and methods of tailoring a composition to achieve a particular set of mechanical properties.

However, the scope of application of the resins manufactured in accordance with [14] is rather limited, hence, there is a need for composite metamaterials with broader application range.

Same is valid for the thermoplastic resin described in the United States Patent: 9,123,893 [15], where the resin is reinforced by a pre-manufactured dispersion of nanotubes. However, the method of preparing such dispersion is not disclosed.

Another the United States Patent 9, 159,463 [16] describes a conductive material which material includes a carbon substance and a metallic substance mixed with and/or laminated to the carbon substance. The carbon substance has at least one dimension of 200 nm or less. The carbon substance includes a graphene selected from single-layered graphene and multi-layered graphene, a part of carbon atoms constituting the graphene is substituted with a nitrogen atom. The metallic substance includes at least one of a metallic particle and a metallic wire. The conductive material, wherein I.sub.401.2 representing intensity at 401.2 eV is higher than I.sub.398.5 representing an intensity at 398.5 eV in X-ray photoelectron spectrum with a 1 s electron of the nitrogen atom. The present invention offers much higher performance, namely, it works at 600MeV, and the material does not include any metallic particles.

The present invention has been made in view of the above-described problems of the conventional techniques and an object of the present invention is to provide a nanocomposite capable of high dispersibility in a liquid cocktail comprising perfluorocarbon solvent and a dispersion comprising the nanocomposite. Specifically, the nanocomposite produced in accordance with the present invention comprises a graphene-based nanostructure where the graphene nanoparticles, platelets or nanotubes are evenly distributed within perfluorotributylamine forming a two-tier regular grid with cell dimension in the range of 15 to 25nm.

The method of producing the metamaterial in question comprises the steps of:

- preparing the graphene-capturing surface by means of

• spreading a mixture of N, N-Dimethylformamide and tetrahydrofuran in a ratio range of 1 : 1 to 3: 1 (v/v) over the inner surface of a container made of thermally stable and chemically neutral substance. In the experiments, borosilicate glass with Si0 ₂ content of, at least, 80 % and B ₂ 0 ₃ content of, at least, 13 %, was used. Other materials with the similar properties, for example, fine ceramics, can be used;

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

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

- preparing a sub-structural liquid by mixing perfluorotributylamine with graphene platelets, particles or nanotubes at the ratio range of 1 to 15 mg of graphene per 1 ml of perfluorotributylamine;

- spreading the sub-structural liquid over the inner surface of the container;

- cooling the inner surface of the container to the temperature of minus 32 degrees Centigrade to minus 50 degrees Centigrade; - applying magnetic field with intensity of 0.5 to 2.5 Tl to the container for 12 to 24 hours;

- heating the resulting liquid state metamaterial to the temperature range of plus 20 degrees Centigrade to 25 degrees Centigrade.

The resulting substance proved to be capable of high dispersibility in various materials. Moreover, introduction of the substance in question to various materials, such as, for example, fine ceramics, plastics, alloys, solid state polymers, other liquid and amorphous substances, enables even distribution of graphene particles within the material, composing a continuous graphene grid. Thus, the material acquires the features of a metamaterial.

Due to particular properties of the metamaterial in question, a number of practical applications thereof are described, although the list is not exhaustive. One feature of the claimed metamaterial makes it particularly interesting to various fields of industry, namely, the capability of being mixed with, and solidified in, fine ceramics, plastics, alloys, solid state polymers, other liquid and amorphous substances.

Among the most prospective one should indicate the use of the claimed metamaterial for the following purposes:

- Use of the metamaterial as an electric current conductor with the resistance range of 0.0002 Ohm/cm ² to 0.000001 at the temperature range of minus 173 degrees Centigrade to plus 102 degrees Centigrade. The experiments (see Example re Claim 6 further in this description) provided the solid ground for such statement.

- Use of the metamaterial as a shield against radiation and electromagnetic waves, capable of significantly absorbing or/and reflecting radiation within the frequency range of 30MHz AO 30 EHz. The experiments (see Example re. Claim 5 and Figs. 1-5 further in this description) provided the solid ground for such statement.

- Use of the metamaterial as a lubricant capable of maintaining lubrication property within the temperature range of minus 180 degrees Centigrade to plus 700 degrees Centigrade. The corresponding experiments are described in Example re Claim 4, providing the results of testing a thin layer lubricant in extreme temperature conditions.

To enable better understanding of the claimed invention the following drawings are presented:

Fig.1 - Radiation impact test:

1.1 - Before the test. Microchips OFF.

1.2 - Before the test. Microchips ON.

1.3 - X-ray source ON. Before irradiation.

1.4- X-ray source ONN. After irradiation.

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

1.5- Spontaneous reboot process of the control chip (left). Fig. 2 - Testing the lubrication properties of the metamaterial:

2.1 - Spacesuit with lubricated shoulder coupling.

2.2 - Diagram of the lubricant viscosity dependence on temperature. Fig. 3 - Conductivity tests:

3.1 - Electric circuitry (R - test wire). 3.2 - Electric circuitry (X - metamaterial). 3.3 - Diagram of the resistance/temperature dependence.

Example re Claim 4. A thin layer lubricant in extreme temperature conditions.

The metamaterial of Claim 1 and, alternatively, of Claim 2, has been lab tested on a movable component (shoulder coupling) of a standard spacesuit (see Fig. 2.1) exposed to burst pressure of 8 bar (0.79MPa). Sliding capability of two lapped surfaces increased 5 folds. Wear resistance increased 9.5 folds at 100000 cycles (vs 47000 cycles at the lab tests described in Advanced Functional Materials, Volume 24, Issue 42, pages 6640-6646, November 12, 2014 [17]). Having been applied in the ball-bearing segment of the spacesuit motor the lubricant demonstrated 15 folds enhancement of the segment performance. Same results were recorded also at the temperatures of minus 180 degrees Centigrade and plus 700 degrees Centigrade (see Fig. 2.2)..

Example re Claim 5. Shield against radiation.

Below is an example of practical use of the claimed metamaterial as a shield against high dose of X-radiation (see Fig. 1). Experimental and control chips contained a single processor with a random number algorithm, a controller and lamps for visualization. Experimental chip was flooded by the claimed metamaterial (see Claim 1). Chips were not protected by any special varnish. During the irradiation by an X-ray device the chips were switched on and intensely shook on a vibration platform. The test was conducted in two stages by 30 Gray and for 60 minutes each. After 1st stage control chip made spontaneous reboot. After 2nd stage such reboot began to repeat every 20-30 minutes. It should be noted that Robots from Toshiba with U.S. protected chips currently used by TEPCO has also become spontaneously reboot and freezes having worked for 4 hours at a dose 26Gray. Example re Claim 6. Conductivity tests (see Fig. 3).

A simple circuitry comprising R - copper wire and X - metamaterial of Claim 1 and an electric power source, was installed for the experiments. For measurements the Kelvin bridge or another similar device can be used. The copper wire has demonstrated resistance within the range of 0.017 to 0.018 Ohm/cm at the average room temperature. Then, the copper wire has been replaced by a sample made of the metamaterial of Claim 1. The records in this

2 2 case indicated the registered range of 0.0002 Ohm/cm to 0.000001 Ohm/cm at the same room temperature. The experiments were carried out at the wide range of temperature, namely, within the range of minus 173 degrees Centigrade to plus 102 degrees Centigrade. The diagram presented on Fig. 3.3 shows the temperature/resistance dependence. Same results were obtained with the metamaterial of Claim 2.