Dispersion

Abstract

A method for forming a liquid dispersion of 2D material / graphite nanoplatelets is disclosed. The method includes (1) creating a dispersion medium, (2) mixing the 2D material / graphite nanoplatelets into the dispersion medium, and (3) subjecting the 2D material / graphite nanoplatelets to sufficient shear and / or crushing forces to reduce the particle size of the 2D material / graphite nanoplatelets. The liquid dispersion includes the 2D material / graphite nanoplatelets, at least one grinding medium, and at least one non-aqueous solvent.

Description

Technical Field

[0001] The present invention relates to dispersions, and more particularly to dispersions containing two-dimensional (2D) materials and methods for producing such dispersions.

Background Art

[0002] The 2D materials referred to herein include one or more known 2D materials, and / or graphite flakes having at least one nanoscale dimension, or mixtures thereof. These 2D materials are collectively referred to herein as "2D material / graphite nanoplatelets" or "2D material / graphite nanoplate".

[0003] 2D materials (sometimes referred to as monolayer materials) are crystalline materials consisting of a single layer or up to a few layers of atoms. Stacked 2D materials consist of 2D layers that are weakly stacked or bonded to form a three-dimensional structure. The nanoplatelets of 2D materials have a thickness below the nanoscale, and the other two dimensions are generally on a scale larger than the nanoscale.

[0004] Known 2D nanomaterials include graphene (C), graphene oxide, reduced graphene oxide, hexagonal boron nitride (hBN), molybdenum disulfide (MoS 2 2), tungsten diselenide (WSe 2 2), silicene (Si), germanene (Ge), graphyne (C), borophene (B), phosphorene (P), or 2D vertical or in-plane heterostructures of two of the aforementioned materials, but are not limited thereto.

[0005] Graphite nanoplatelets having at least one nanoscale dimension contain 10 to 40 layers of carbon atoms and have lateral dimensions in the range of about 100 nm to 100 μm.

[0006] 2D materials / graphene nanoplatelets, and in particular graphene and hexagonal boron nitride, have many interesting properties in the physical world, and many more properties are being discovered. A major challenge for the use of such materials and their properties is to produce compositions in which such materials are dispersed that can be made by commercial processes and are commercially attractive. In particular, such compositions need to have a sufficient storage period / lifetime for the material to be sold, stored for a known period, and then used. Further, such compositions must not be harmful to the user and / or the environment, or at least any harmfulness must be within acceptable limits.

[0007] Specific problems faced in relation to 2D materials / graphene nanoplatelets are their low dispersibility in aqueous and non-aqueous solvents and, once dispersed, the low stability of such dispersions. For example, graphene nanoplatelets and / or graphite nanoplatelets having one nanoscale dimension face this problem in aqueous and non-aqueous solvents. Hexagonal boron nitride nanoplatelets also face the same problem.

[0008] For 2D materials / graphene nanoplatelets known or suspected to be harmful, especially when not encapsulated in other materials, the stability of those 2D materials / graphene nanoplatelets in the dispersion is particularly important. This is because when those 2D materials / graphene nanoplatelets separate and dry out of the dispersion when not bound or encapsulated in a non-aerosolized material, they easily become aerosolized. Aerosolized graphene nanoplatelets and / or graphite nanoplatelets having at least one nanoscale dimension are thought to be able to cause harm to human and animal health if inhaled into the lungs. The harmfulness of other 2D materials / graphite plateletlets is still being evaluated, but it is considered prudent to assume that other 2D materials / graphene nanoplatelets will exhibit similar harmfulness.

[0009] 2D materials / graphene nanoplatelets have a large surface area and low functionality, and historically it has been proven difficult to wet and / or disperse them in solution. Furthermore, it is known that it is very difficult to prevent aggregation of once-dispersed 2D materials / graphene nanoplatelets.

[0010] Improvement of methods for achieving wetting and dispersion stability has been an active area of research since the discovery of 2D materials / graphene nanoplatelets and their properties.

[0011] Parameters for making good dispersions are well established in the field of colloid science, and the free energy of any colloidal system is determined by both the interfacial area and the interfacial tension. The theoretically calculated surface area of a single layer of graphene is about 2590 m 2 g -1 , and as a result the range of conditions under which it can be dispersed is limited, and these conditions typically included sonication and polar aprotic solvents.

[0012] In order to maintain the stability of graphene / graphene platelets (where graphene nanoplatelets are graphene nanoplatelets having nanoscale dimensions, 10 - 20 layers, and lateral dimensions in the range of about 100 nm - 100 μm) in a dispersion when they are dispersed, it is necessary to generate an energy barrier to prevent aggregation of those nanoplatelets. This can be achieved by either electrostatic or steric repulsive forces. If the energy barrier is high enough, Brownian motion will maintain the dispersion. This has been achieved by using one or more approaches that can be characterized as follows. a. Solvent selection, b. Chemical (covalent) modification of graphene / graphene nanoplatelets, and c. Non-covalent modification of graphene / graphene nanoplatelets.

[0013] a. Selection of solvent Several solvents, particularly N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), and dimethylformamide (DMF), have been identified as being particularly good for the dispersion of graphene / graphite platelets. These solvents have health and safety issues, and it is desirable not to use these solvents.

[0014] Solvent interactions have been reasonably explained by both the use of surface energy and Hansen solubility parameters. By using Hansen solubility parameters, several solvents have been identified as potential carrier media, but their effectiveness depends on the functionality of the graphene / graphite platelets, the mode of dispersion, the time from dispersion, and / or the temperature of the dispersion.

[0015] When an improvement in dispersion was achieved using Hansen solubility parameters, this was thought to be due to the development of a layer of solvent on the surface of the graphene / graphite platelets. However, usually, the resulting energy barrier is small due to steric interactions, and such dispersions aggregate within a few days of production.

[0016] b. Chemical (covalent) modification of graphene / graphite platelet The functionalization of graphene / graphite nanoplatelets depends significantly on the level of availability of functional groups. When oxygen is present (such as in reduced graphene oxide), one of the most common routes is to introduce functionality using diazonium salts.

[0017] Alternatively, when the functionality is absent (pure graphene or graphite) or very low, plasma modification may be used to introduce functionality. These graphene / graphite nanoplatelets may then be further processed to generate new functional species. The most important process parameter for plasma treatment is the process gas. This is because the process gas defines the chemical groups introduced, while the process time and power used affect the concentration of the functional groups introduced.

[0018] It has been observed that the chemical functionalization of graphene / graphite nanoplatelets can improve their dispersibility, but it can also increase their own defects and have an adverse effect on their properties. This is clearly an undesirable result.

[0019] c. Non-covalent modification of graphene / graphite nanoplatelet The non-covalent modification of graphene / graphite nanoplatelets has several advantages over covalent modification in that it does not involve additional chemical steps and avoids damage to the sp2 domains within the platelet. Various interactions are possible, and the principles are π-π, cation-π, and the use of surfactants.

[0020] The π-π bond may be achieved through either dispersive or electrostatic interactions. For example, a wide range of aromatic-based systems such as polyaromatic hydrocarbons (PAHs), pyrene, and polyacrylonitrile (PAN) have been shown to interact with graphene.

[0021] The cation-π bond may use either a metal or an organic cation. Generally, organic cations are preferred, and imidazolium cations are preferred because of their planar aromatic structure.

[0022] Due to the availability of a variety of surfactants commercially, surfactants are widely used. Usually, the surfactant is first adsorbed on the basal edge of the nanoplate and then on the surface. Adsorption is promoted when there is the ability of π-π interaction and a planar tail that can be solvated. Based on the functionality of the basal edge and surface of graphene / graphite nanoplatelets and the medium in which the graphene / graphite nanoplatelets are dispersed, both nonionic and ionic surfactants have been shown to be effective.

[0023] Summarizing the above considerations, highly specific additives are required to wet, disperse, and stabilize the dry powder of graphene / graphite nanoplatelets for use in liquid formulations. It is understood that the same applies to other 2D materials / graphite nanoplatelets.

Summary of the Invention

Means for Solving the Problems

[0024] According to a first aspect of the present invention, there is provided a method of forming a liquid dispersion of a 2D material / graphite nanoplatelet, the method comprising: (1) a step of preparing a dispersion medium; (2) a step of mixing the 2D material / graphite nanoplatelet with the dispersion medium; (3) a step of subjecting the 2D material / graphite nanoplatelet to sufficient shear force and / or crushing force to reduce the particle size of the 2D material / graphite nanoplatelet using mechanical means, wherein the mixture of the 2D material / graphite nanoplatelet and the dispersion medium comprises the 2D material / graphite nanoplatelet, at least one grinding medium, and at least one non-aqueous solvent.

[0025] According to a second aspect of the present invention, there is provided a liquid dispersion comprising a 2D material / graphite nanoplatelet, at least one grinding medium, and at least one non-aqueous solvent.

[0026] According to a third aspect of the present invention, a liquid coating system is provided that includes the liquid dispersion according to the second aspect of the present invention.

[0027] In some embodiments of the first aspect of the present invention, the 2D material / graphene nanoplatelet includes one or more graphene or graphene nanoplatelets, where the graphene nanoplatelet is a graphene nanoplate, reduced graphene oxide nanoplate, bilayer graphene nanoplate, bilayer reduced graphene oxide nanoplate, trilayer graphene nanoplate, trilayer reduced graphene oxide nanoplate, few-layer graphene nanoplate, few-layer reduced graphene oxide nanoplate, and one or more of graphene nanoplatelets having 6 to 10 layers of carbon atoms, and the graphite nanoplatelet includes graphite nanoplatelets having at least 10 layers of carbon atoms.

[0028] In some embodiments of the present invention, one or both of the graphene nanoplatelet and the graphite nanoplatelet have a lateral dimension in the range of about 100 nm to 100 μm.

[0029] In some embodiments of the first aspect of the present invention, the 2D material / graphene nanoplatelet includes one or more graphite nanoplatelets, where the graphite nanoplatelet is a graphite nanoplate having 10 to 20 layers of carbon atoms, a graphite nanoplate having 10 to 14 layers of carbon atoms, a graphite nanoplate having 10 to 35 layers of carbon atoms, a graphite nanoplate having 10 to 40 layers of carbon atoms, a graphite nanoplate having 25 to 30 layers of carbon atoms, a graphite nanoplate having 25 to 35 layers of carbon atoms, a graphite nanoplate having 20 to 35 layers of carbon atoms, or a graphite nanoplate having 20 to 40 layers of carbon atoms.

[0030] In some embodiments of the first aspect of the present invention, the 2D material / graphene nanoplatelet includes one or more 2D material nanoplatelets, where the 2D material nanoplatelet is hexagonal boron nitride (hBN), molybdenum disulfide (MoS 2 )), tungsten diselenide (WSe2 ) including one or more of silicon (Si), germanene (Ge), graphene (C), borophene (B), phosphorene (P), or 2D in-plane or vertical heterostructures of two or more of the foregoing materials.

[0031] Few-layer graphene / reduced graphene oxide nanoplatelets have 4 to 10 layers of carbon atoms, where a single layer has a thickness of 0.035 nm and a typical interlayer distance of 0.14 nm.

[0032] In some embodiments of the first aspect of the present invention, the 2D material / graphite nanoplatelets include graphene / graphite nanoplatelets.

[0033] In some embodiments of the first aspect of the present invention, at least one grinding medium is a solid (including powder), the dispersion medium includes at least one solid grinding medium and at least one non-aqueous solvent, and the step of preparing the dispersion medium is (i) dissolving at least one solid grinding medium in at least one solvent; and (ii) mixing the grinding medium solution until it becomes substantially homogeneous.

[0034] In some embodiments of the first aspect of the present invention, at least one grinding medium is a liquid, the dispersion medium includes at least one liquid grinding medium and at least one non-aqueous solvent, and the step of preparing the dispersion medium is (i) including the step of mixing the grinding medium solution in at least one non-aqueous solvent until it becomes substantially homogeneous.

[0035] In some embodiments of the first aspect of the present invention, the method is (iii) after completion of (ii) for at least one solid grinding medium or (i) for at least one liquid grinding medium, adding the 2D material / graphite nanoplatelets to the at least one grinding medium solution; and (iv) mechanically mixing a mixture of the 2D material / graphite nanoplatelets and at least one grinding media solution until the 2D material / graphite nanoplatelets are substantially dispersed in the grinding media solution.

[0036] Preferred grinding media include, but are not limited to, grinding resins, polymers modified with strong anchor groups, aldehyde resins, and Laropal™ A81, which is an aldehyde resin. Laropal A81 is commercially available from BASF, Dispersions & Resins Division, North America.

[0037] Preferred non-aqueous solvents for use in the present invention include, but are not limited to, organic solvents. Preferred solvents are butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2-butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, parachlorobenzotrifluoride, tert-butyl acetate, propylene carbonate, and (1R)-7,8-dioxabicyclo[3.2.1]octan-2-one, or a mixture of two or more of these solvents, or including them. (1R)-7,8-Dioxabicyclo[3.2.1]octan-2-one is commercially available from Merck KGaA, Germany, as Cyrene™.

[0038] In some embodiments, the addition of the solvent is performed after a predetermined operating period of the dispersing means.

[0039] Dry 2D material / graphite nanoplatelets, such as graphene / graphite nanoplatelets, are typically made up of primary particles or aggregates or agglomerates of nanoplatelets. During the dispersion process, those aggregates or agglomerates need to be broken down as much as possible into primary particles or nanoplatelets of a size suitable for the intended application of the 2D material / graphite nanoplatelets.

[0040] In some embodiments of the present invention, the dispersing means is a means suitable for applying both crushing action and mechanical shear force to the materials while the 2D material / graphene nanoplatelets are mixed with the dispersion medium. Suitable apparatuses for achieving this are known grinding or milling apparatuses such as, for example, a dissolver, a bead mill, or a three-roll mill.

[0041] In some embodiments of the present invention, it is preferable that the aggregates or agglomerates are broken down into particles or nanoplatelets of a particle size that cannot be broken down any further. This is beneficial because the production and storage of 2D material / graphene nanoplatelets before use are often carried out in the form of larger particles than desired for the 2D material / graphene nanoplatelet dispersion.

[0042] When the aggregates or agglomerates of 2D material / graphene nanoplatelets are reduced to smaller particles or nanoplatelets, preventing re-aggregation or re-agglomeration of those particles or nanoplatelets is assisted by rapidly stabilizing the newly formed surface resulting from the size reduction of the aggregates or agglomerates.

[0043] The method of the present invention is particularly beneficial because it has been found that the higher the interfacial tension between the dispersion medium, such as a dispersion medium containing a solvent, and the 2D material / graphene nanoplatelets, the stronger the force to reduce the interfacial area. In other words, the force to re-aggregate or re-agglomerate the 2D material / graphene nanoplatelets or to form aggregates becomes stronger. In order to achieve control of the interfacial tension between the dispersion medium and the 2D material / graphene nanoplatelets, wetting agents are generally used. In this way, the wetting agent helps to stabilize the newly formed surface and prevent aggregation, agglomeration, and / or coagulation of the 2D material / graphene nanoplatelets.

[0044] The action of the wetting agent to stabilize the newly formed surface and prevent aggregation, agglomeration, and / or coagulation of the 2D material / graphene nanoplatelets is beneficial, but has been found to result in the following adverse outcomes. a) The characteristic of the 2D material / graphene nanoplatelets is that they have a large surface area compared to other compounds. This large surface area results in the 2D material / graphene nanoplatelets effectively binding to all wetting agents in the dispersion medium. This will have the effect that other compounds in the dispersion medium are found to sediment from the dispersion more rapidly than desired. b) Increasing the proportion of the wetting agent in the dispersion medium may ultimately result in a dispersion in which all components remain suspended. However, this approach to forming the dispersion has the problem that the coating formed from this dispersion will have a high degree of water solubility. This is highly undesirable as it leads to rapid breakdown of the coating.

[0045] According to the present invention, the dispersion is improved by applying a dispersion means to apply a crushing action and / or mechanical shear force to a mixture of the 2D material / graphene nanoplatelets in a grinding medium and a solvent solution.

[0046] The advantage of the method of the present invention is that the milling performance of the dispersion means when acting on the 2D material / graphene nanoplatelets is further improved by the presence of the grinding medium in the mixture to be milled. The improvement is shown by faster milling, a reduction in heat generation in the milling process, a more uniform particle size in the dispersion, a smaller D50 particle size in the dispersion, a reduction in the viscosity of the dispersion, higher storage stability compared to dispersions with a known short shelf life, and the ability to redisperse any combination of grinding resin / 2D material / graphene nanoplatelet particles that had sedimented from the dispersion by simple stirring of the dispersion.

[0047] According to a second aspect of the present invention, there is provided a liquid dispersion comprising a 2D material / graphene nanoplatelet, at least one grinding medium, and at least one non-aqueous solvent.

[0048] In some embodiments of the second aspect of the present invention, the 2D material / graphene nanoplatelet comprises one or more of graphene nanoplatelets, graphite nanoplatelets, and 2D material nanoplatelets. The graphene nanoplatelets include one or more of graphene nanoplates, reduced graphene oxide nanoplates, bilayer graphene nanoplates, bilayer reduced graphene oxide nanoplates, trilayer graphene nanoplates, trilayer reduced graphene oxide nanoplates, few-layer graphene nanoplates, few-layer reduced graphene oxide nanoplates, and graphene nanoplates with 6 to 10 layers of carbon atoms. The graphite nanoplatelets include graphite nanoplates having at least 10 layers of carbon atoms, and the graphite nanoplatelets include one or more of graphite nanoplates having 10 to 20 layers of carbon atoms, graphite nanoplates having 10 to 14 layers of carbon atoms, graphite nanoplates having 10 to 35 layers of carbon atoms, graphite nanoplates having 10 to 40 layers of carbon atoms, graphite nanoplates having 25 to 30 layers of carbon atoms, graphite nanoplates having 25 to 35 layers of carbon atoms, graphite nanoplates having 20 to 35 layers of carbon atoms, or graphite nanoplates having 20 to 40 layers of carbon atoms. The 2D material nanoplatelets include hexagonal boron nitride (hBN), molybdenum disulfide (MoS 2 ), tungsten diselenide (WSe 2 ), silicene (Si), germanene (Ge), graphyne (C), borophene (B), phosphorene (P), or one or more of 2D in-plane or vertical heterostructures of two or more of the aforementioned materials.

[0049] In some embodiments of the second aspect of the present invention, at least one grinding medium comprises one or more of a grinding resin, a polymer modified with a strong anchor group, an aldehyde resin, or a mixture of two or more such media. Preferred grinding media include, but are not limited to, Laropal™ A81, an aldehyde resin commercially available from BASF, Dispersions & Resins Division, North America.

[0050] In some embodiments of the second aspect of the present invention, at least one non-aqueous solvent comprises one or more of an organic solvent, butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2-butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, parachlorobenzotrifluoride, tert-butyl acetate, propylene carbonate, and (1R)-7,8-dioxabicyclo[3.2.1]octan-2-one, or a mixture of two or more of these solvents. (1R)-7,8-Dioxabicyclo[3.2.1]octan-2-one is commercially available from Merck KGaA, Germany under the trade name Cyrene™.

[0051] In some embodiments of the second aspect of the present invention, the liquid dispersion is produced using the method according to the first aspect of the present invention.

[0052] For a better understanding of the various examples useful for understanding the detailed description, reference will now be made, by way of example only, to the accompanying drawings.

Brief Description of the Drawings

[0053]

Figure 1

Figure 2

Figure 3

Mode for Carrying Out the Invention

Examples

[0054] Using the method of the present invention, a dispersion of graphene / graphite material was produced, and comparative samples were prepared using other techniques.

[0055] All dispersions were produced in a horizontal bead mill. The dispersions were milled for 15 minutes in the recirculation mode at maximum speed.

[0056] Characterization of the dispersion The particle size was measured in a Mastersizer 3000 to determine the effectiveness of the grinding resin and dispersant for deagglomeration and particle size reduction.

[0057] Viscosity was measured to assist in understanding the rheological properties of the dispersions. This was done using a Kinexus Rheometer.

[0058] The storage stability was determined by using a Turbiscan Stability Analyser. The Turbiscan Stability Index (TSI) is a relative measure of stability that enables comparison of multiple samples. It enables a quantifiable evaluation of formulations that are closely related as a relative measure.

Examples

[0059] Example 1: Butyl acetate dispersion of graphite material A-GNP10 Samples of dispersions referred to as BA1 to BA3 were prepared, containing graphite material A - GNP10 and butyl acetate as shown in Table 1.

[0060]

Table 1

[0061] The graphite material A-GNP10 is commercially available from Applied Graphene Materials UK Limited, UK, and contains graphite nanoplatelets with a thickness of 25 to 35 atomic layers. The graphite nanoplatelets are supplied as a powder and are generally aggregated into lumps of nanoplatelets.

[0062] Each of Samples BA1 to BA3 was prepared using the following steps. 1 Any crushed resin and / or wetting agent present in the sample was added to butyl acetate. This was stirred until all solids were dissolved and the mixture became substantially homogeneous. 2 10 wt% of AGNP-10 was calculated based on the weight of butyl acetate and added to the mixture, and the mixture was stirred until the powder was uniformly dispersed in the mixture. 3 The mixture was bead milled by recirculation in a bead mill using beads for 15 minutes.

[0063]

Table 2

[0064]

Table 3

[0065] Figure 1 provides a graph showing the relationship between viscosity and shear rate for Samples BA1 to BA3 in Table 1.

[0066]

Table 4

[0067]

Table 5

[0068] The use of a wetting agent provides a slight improvement in the graphene dispersion in butyl acetate. The use of a ground resin significantly reduces sedimentation and synereisis, while having no effect on the final performance characteristics.

Examples

[0069] Example 2: Methyl ethyl ketone dispersion of graphite material A-GNP10 Samples of dispersions referred to as MEK1 to MEK3, containing the graphite material A-GNP10 and methyl ethyl ketone as shown in Table 6, were prepared.

[0070]

Table 6

[0071] Each of the samples MEK1 to MEK3 was prepared using the same steps as those used in relation to the samples BA1 to BA3 shown above.

[0072]

Table 7

[0073]

Table 8

[0074] Figure 2 provides a graph showing the relationship between viscosity and shear rate for the samples MEK1 to MEK3 of Table 6.

[0075]

Table 9

[0076]

Table 10

[0077] The use of a wetting agent provides an improvement in the graphene dispersion in methyl ethyl ketone. However, as shown by the resulting TSI and the lack of significant destabilization with the use of a milled resin, the dispersion stability is significantly improved. No effect on the final performance characteristics was observed.

Examples

[0078] Example 3: Xylene dispersion of graphite material A-GNP10 Samples of dispersions referred to as X1 - X3 were prepared, containing graphite material A - GNP10 and xylene as shown in Table 11.

[0079]

Table 11

[0080] Each of the samples X1 - X3 was prepared using the same steps as those used in connection with samples BA1 - BA3 shown above.

[0081]

Table 12

[0082]

Table 13

[0083] Figure 3 provides a graph showing the relationship between viscosity and shear rate for samples X1 - X3 of Table 11.

[0084]

Table 14

[0085]

Table 15

[0086] The use of wetting agents provides a slight improvement in the graphene dispersion in xylene. However, while the use of the milled resin significantly reduces sedimentation and synereisis as shown, the resulting TSI does not show significant destabilization. No effect on the final performance characteristics was observed.

Claims

Claim 1 A method for forming a liquid dispersion of a 2D material / graphene nanoplatelet, the method comprising: (1) preparing a dispersion medium by mixing at least one grinding medium containing Laropal (trademark) A81 and at least one non-aqueous solvent until substantially homogeneous; (2) mixing the 2D material / graphene nanoplatelet into the dispersion medium; (3) subjecting the 2D material / graphene nanoplatelet to shear force and / or crushing force sufficient to reduce the particle size of the 2D material / graphene nanoplatelet. The liquid dispersion contains the 2D material / graphene nanoplatelet, the at least one grinding medium, and the at least one non-aqueous solvent. The 2D material / graphene nanoplatelet includes one or more of graphene nanoplatelets, graphite nanoplatelets, and 2D material nanoplatelets. The graphene nanoplatelets include one or more of graphene nanoplatelets, reduced graphene oxide nanoplatelets, bilayer graphene nanoplatelets, bilayer reduced graphene oxide nanoplatelets, trilayer graphene nanoplatelets, trilayer reduced graphene oxide nanoplatelets, few-layer graphene nanoplatelets, few-layer reduced graphene oxide nanoplatelets, and graphene nanoplatelets with 6-10 layers of carbon atoms. The graphite nanoplatelets include graphite nanoplatelets having at least 10 layers of carbon atoms. The graphite nanoplatelets include one or more of graphite nanoplatelets having 10-20 layers of carbon atoms, graphite nanoplatelets having 10-14 layers of carbon atoms, graphite nanoplatelets having 10-35 layers of carbon atoms, graphite nanoplatelets having 10-40 layers of carbon atoms, graphite nanoplatelets having 25-30 layers of carbon atoms, graphite nanoplatelets having 25-35 layers of carbon atoms, graphite nanoplatelets having 20-35 layers of carbon atoms, and graphite nanoplatelets having 20-40 layers of carbon atoms. The 2D material nanoplatelets include hexagonal boron nitride (hBN), molybdenum disulfide (MoS ２ ), tungsten diselenide (WSe ２ ), silicene (Si), germanene (Ge), graphene (C), borophene (B), phosphorene (P), and one or more of 2D in-plane or vertical heterostructures including two or more of these materials. Claim 2 The method according to claim 1, wherein the at least one non-aqueous solvent includes one or more of an organic solvent, butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2-butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, para-chlorobenzotrifluoride, tert-butyl acetate, propylene carbonate, (1R)-7,8-dioxabicyclo[3.2.1]octan-2-one, and a mixture of two or more of these solvents.

3. The method according to claim 1 or 2, wherein step (3) of subjecting the mixture of the 2D material / graphene nanoplatelet and the dispersion medium to a shearing force and / or a crushing force is performed using one or more of a dissolver, a bead mill, and a three-roll mill.

4. Comprising a 2D material / graphene nanoplatelet, at least one grinding medium, and at least one non-aqueous solvent, wherein the at least one grinding medium includes Laropal (trademark) A81, wherein the 2D material / graphene nanoplatelet includes one or more of a graphene nanoplatelet, a graphite nanoplatelet, and a 2D material nanoplatelet, wherein the graphene nanoplatelet includes one or more of a graphene nanoplate, a reduced graphene oxide nanoplate, a bilayer graphene nanoplate, a bilayer reduced graphene oxide nanoplate, a trilayer graphene nanoplate, a trilayer reduced graphene oxide nanoplate, a few-layer graphene nanoplate, a few-layer reduced graphene oxide nanoplate, and a graphene nanoplate having 6 to 10 layers of carbon atoms, wherein the graphite nanoplatelet includes a graphite nanoplate having at least 10 layers of carbon atoms, wherein the graphite nanoplatelet includes one or more of a graphite nanoplate having 10 to 20 layers of carbon atoms, a graphite nanoplate having 10 to 14 layers of carbon atoms, a graphite nanoplate having 10 to 35 layers of carbon atoms, a graphite nanoplate having 10 to 40 layers of carbon atoms, a graphite nanoplate having 25 to 30 layers of carbon atoms, a graphite nanoplate having 25 to 35 layers of carbon atoms, a graphite nanoplate having 20 to 35 layers of carbon atoms, and a graphite nanoplate having 20 to 40 layers of carbon atoms, The 2D material nanoplatelets include hexagonal boron nitride (hBN), molybdenum disulfide (MoS ２ ), tungsten diselenide (WSe ２ ), silicene (Si), germanene (Ge), graphene (C), borophene (B), phosphorene (P), and one or more of 2D in-plane or vertical heterostructures containing two or more of these materials, a liquid dispersion.

5. The at least one non-aqueous solvent includes one or more of an organic solvent, butyl acetate, xylene, ethyl acetate, methyl ethyl ketone, butanol, 2-butoxyethanol, other glycol ethers, acetone, dimethyl carbonate, methyl acetate, parachlorobenzotrifluoride, tert-butyl acetate, propylene carbonate, (1R)-7,8-dioxabicyclo[3.2.1]octan-2-one, and a mixture of two or more of these solvents, the liquid dispersion according to claim 4.

6. A liquid coating composition comprising the liquid dispersion according to claim 4 or 5.

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