Modified graphene dispersion liquid containing high-concentration salt as well as preparation method and application of modified graphene dispersion liquid

Abstract

The invention discloses a modified graphene dispersion liquid containing high-concentration salt and a preparation method and application thereof.The method comprises the steps that firstly, carboxyl groups on graphene oxide are subjected to acylating chlorination modification, and then a series of modified graphene oxide with the grafting cation number and density controllable is synthesized through stepwise polymerization reaction; the synthesis of the structure-controllable cationic modified graphene oxide is realized. The cationic modified graphene oxide can be stably dispersed in a high-concentration salt solution, and the number of cations required on a side chain can be calculated in advance according to the specific salt concentration.

Description

Technical Field

[0001] This invention belongs to the field of graphene materials, specifically relating to a modified graphene dispersion containing a high concentration of salt, its preparation method, and its application. Background Technology

[0002] Graphene oxide, with its unique two-dimensional layered structure and abundant oxygen-containing functional groups on its surface (such as carboxyl, epoxy, and hydroxyl groups), shows broad application prospects in energy storage, composite materials, biomedicine, and separation membranes. Compared with pristine graphene, graphene oxide has better hydrophilicity and solution processability, and can form stable colloidal dispersions in water. These properties make graphene oxide an ideal basic material for preparing various functional materials.

[0003] Graphene oxide dispersions exhibit poor long-term stability under high-concentration inorganic salt environments, readily undergoing flocculation and sedimentation. These changes not only affect the dispersion stability of graphene oxide but also further impact its subsequent functionalization and the performance of composite materials. For many applications, such as fuel cells and ion exchange membranes, developing graphene oxide materials with excellent dispersion stability under heavy salt conditions is crucial.

[0004] To improve the dispersibility of graphene oxide in different media, researchers have developed various modification methods, mainly including surfactant modification, silane coupling agent modification, polymer grafting modification, and ionic liquid modification. A common limitation of existing technologies is the inability to design specific molecular structures for heavy salt environments, and the long-term stability, redispersibility, and functional retention of modified graphene oxide under heavy salt conditions remain unsatisfactory. Summary of the Invention

[0005] To address the difficulty in preparing stably dispersed graphene oxide dispersions under heavy salt conditions in existing technologies, this application proposes a modified graphene dispersion containing a high concentration of salt, its preparation method, and its applications. This invention introduces stable cationic groups through molecular design to enhance electrostatic stabilization under heavy salt conditions.

[0006] In high-ion-concentration environments, appropriately cationic modified graphene oxide can effectively resist the destructive effects of metal salt ions by generating strong electrostatic repulsion through its surface positive charge, thus maintaining excellent dispersion stability. For cationic side chains with controllable sequences, the spacing and number of side chain cations can be precisely designed for specific ion concentrations and types, enabling targeted structural designs in different environments and achieving uniform and stable dispersion.

[0007] In addition, cationic side chains can introduce new functional properties into graphene oxide, such as ion exchange capacity and antibacterial activity, further expanding its application areas.

[0008] One of the technical solutions of this invention is to provide a modified graphene dispersion containing a high concentration of salt, which is composed of cationic modified graphene oxide, inorganic salt and water. The cationic modified graphene oxide contains side chains with a controllable number of cations, and the controllable number n of cations on a single side chain satisfies the following constraint condition: C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; Where C is the concentration of inorganic salts, [H] is the hydrogen ion concentration in a 0.1 wt% aqueous solution of unmodified graphene oxide, e is the total charge of inorganic salt cations, and ρ is the concentration of modified graphene. The concentration of inorganic salts is expressed in mg / mL, and the concentration ρ of modified graphene is expressed in mg / mL.

[0009] For different inorganic salt cation concentrations, cationic modified graphene oxide with different numbers of cation grafts on a single side chain can be designed and prepared. These modified graphene oxides are dispersed in an inorganic salt solution and stirred for 2-4 hours to obtain a uniform and stable graphene oxide dispersion containing a high concentration of salt.

[0010] The second technical solution of the present invention is to provide a method for preparing the above-mentioned modified graphene dispersion, comprising the following steps: (1) Graphene oxide is dispersed in a solvent, excess thionyl chloride is added, the mixture is stirred for 4-12 hours, and the supernatant is removed after centrifugation to obtain acyl-chlorinated graphene oxide; the mass ratio of thionyl chloride to graphene oxide is not less than 1:1; the chemical reaction formula is as follows: ; (2) The acyl chloride graphene oxide obtained in step (1) is dispersed in a solvent, a hydroxy-alkynyl compound and an acid-binding agent are added, the mixture is stirred for 4-12 hours, the supernatant is removed after centrifugation, and alkynylated graphene oxide is obtained; the mass ratio of the acyl chloride graphene oxide, the hydroxy-alkynyl compound and the acid-binding agent is 1-20:5-200:1-10; its chemical reaction formula is as follows: ; (3) The acetylated graphene oxide obtained in step (2) is dispersed in a solvent, and an azide-amine compound and a copper catalyst are added. The mixture is stirred and reacted under inert gas protection. After centrifugation, the precipitate is collected to obtain tertiary amine-modified graphene oxide. The mass ratio of the acetylated graphene oxide, the azide-amine compound, and the copper catalyst is 1-20:5-200:3-10. The chemical reaction formula is as follows: ; (4) Disperse the tertiary amino-modified graphene oxide obtained in step (3) in a solvent, add bromopropyne, stir for 2-12 hours, collect the precipitate after centrifugation, and obtain alkynyl-modified graphene oxide; the mass ratio of the tertiary amino-modified graphene oxide to bromopropyne is 1-20:5-200. Its chemical reaction formula is as follows: ; (5) Repeat steps (3) and (4) to obtain cationic modified graphene oxide.

[0011] Each repetition of steps (3) and (4) adds a cation to the cationic modified graphene oxide.

[0012] (6) Dissolve the inorganic salt in a solvent to form an inorganic salt solution, and disperse the cationic modified graphene oxide obtained in step (5) in the inorganic salt solution. The concentration C of the inorganic salt and the number n of cations on the cationic modified graphene oxide satisfy the following formula: C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; Where C is the concentration of inorganic salt, [H] is the hydrogen ion concentration in a 0.1 wt% aqueous solution of unmodified graphene oxide, e is the total charge of inorganic salt cations, and ρ is the concentration of modified graphene.

[0013] The cations of inorganic salts are selected from aluminum ions, calcium ions, sodium ions, and potassium ions; the anions are selected from sulfate ions, chloride ions, and nitrate ions.

[0014] Further, the solvent is N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, or a mixture of the above solvents in any proportion.

[0015] Further, the hydroxy-alkynyl compound in step (2) is selected from ethynyl alcohol, propynyl alcohol, butynyl alcohol, pentylyl alcohol, hexynyl alcohol, heptylyl alcohol, octylyl alcohol or homologues whose main chain contains more methylene groups.

[0016] Furthermore, the acid-binding agent mentioned in step (2) is selected from pyridine, triethylamine, and dimethylaminopyridine.

[0017] Further, the azido-amine compound in step (3) is selected from dimethylazidoethylamine, dimethylazidopropylamine, dimethylazidobutylamine, dimethylazidopentylamine, dimethylazidohexylamine, dimethylazidoheptylamine, dimethylazidooctylamine, or homologues whose main chain contains more methylene groups.

[0018] Furthermore, the copper catalyst mentioned in step (3) is selected from cuprous chloride, cuprous bromide, and elemental copper.

[0019] Furthermore, the concentrations of graphene oxide in step (1), acyl chloride graphene oxide in step (2), alkynylated graphene oxide in step (3), and tertiary amine-modified graphene oxide in step (4) are 1-20 mg / mL.

[0020] The third technical solution of the present invention is to provide the application of the above-mentioned modified graphene dispersion containing high concentration of salt.

[0021] Compared with the prior art, the advantages of the present invention are: (1) By grafting graphene oxide through this method, the number and density of cations on the side branches, the structure and length of the grafted molecular chains can be precisely designed and controlled, and targeted structural design can be completed under different inorganic salt types and concentrations, so as to achieve stable and uniform dispersion in different environments.

[0022] (2) In a high-concentration inorganic salt environment, cationic oxidation can generate a strong electrostatic repulsion through its surface positive charge, thereby maintaining excellent dispersion stability. In addition, cationic side chains can also introduce new functional properties to graphene oxide, such as ion exchange capacity and antibacterial activity.

[0023] (3) The preparation method has mild reaction conditions, high yield, simple post-processing, reusable reactants, precise and controllable cation grafting structure, and is easy to industrialize. Attached Figure Description

[0024] Figure 1 The infrared spectra (b) are those of the second-generation alkynylated graphene oxide (a) and the second-generation tertiary amine-modified graphene oxide in Example 1.

[0025] Figure 2 The images are from Example 1, showing the results of shaking and standing for 12 hours in aluminum sulfate solutions of 50 mg / mL and 100 mg / mL.

[0026] Figure 3 Photographs of cationic modified graphene oxide prepared in Examples 3 and 4, after shaking and standing for 12 hours in a 300 mg / mL calcium chloride solution. Detailed Implementation

[0027] The following examples are provided to further illustrate the present invention and are intended to explain the invention, not to limit its scope. Unless otherwise specified, all figures are expressed in parts by weight and weight percentages.

[0028] Unless otherwise specified, the raw materials used in this invention are all conventional commercially available products; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0029] The embodiments of the present invention will be further described below with reference to several examples.

[0030] It should be understood that the described embodiments are merely some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without inventive effort are within the scope of protection of this application.

[0031] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0032] Example 1 (1) 1g of graphene oxide was dispersed in 100ml of dimethylacetamide. The hydrogen ion concentration of the 0.1% aqueous dispersion of graphene oxide was 1*10. -5 Add 1 g of thionyl chloride to a solution of mol / L, stir the mixture at room temperature for 12 hours, centrifuge to remove the supernatant, and collect the precipitate. Disperse the precipitate in dimethylacetamide, then centrifuge again to precipitate, repeating the process twice. Collect the precipitate to obtain acyl-chlorographene oxide.

[0033] (2) Disperse 1g of the acyl-chlorinated graphene oxide obtained in step (1) in 100ml of dimethylacetamide, add 3g of butynol and 0.5g of triethylamine, stir and react for 4 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in dimethylacetamide, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation acyl-chlorinated graphene oxide.

[0034] (3) Disperse 1g of the acetylated graphene oxide obtained in step (2) in 100ml of dimethylacetamide, add 2g of dimethyl azidoethylamine and 0.3g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0035] (4) Disperse 1g of the first-generation tertiary amine-modified graphene oxide obtained in step (3) in 100ml of dimethylacetamide, add 0.5g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in dimethylacetamide, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the second-generation acetylated graphene oxide.

[0036] (5) Disperse 1g of the second-generation acetylated graphene oxide obtained in step (4) in 100ml of dimethylacetamide, add 2g of dimethyl azidoethylamine and 0.3g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the second-generation tertiary amine-modified graphene oxide.

[0037] (6) Disperse 1g of the second-generation tertiary amine-modified graphene oxide obtained in step (5) in 100ml of dimethylacetamide, add 0.5g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the third-generation acetylated graphene oxide.

[0038] (7) Disperse 1g of the third-generation acetylated graphene oxide obtained in step (6) in 100ml of dimethylacetamide, add 2g of dimethyl azidoethylamine and 0.3g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the third-generation tertiary amine-modified graphene oxide.

[0039] (8) Disperse 1g of the third-generation tertiary amine-modified graphene oxide obtained in step (7) in 100ml of dimethylacetamide, add 0.5g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the fourth-generation acetylated graphene oxide, that is, cationic modified graphene oxide with 3 cations in the side chain.

[0040] The infrared image of the obtained product is as follows Figure 1 As shown, the tertiary amino-modified graphene oxide obtained by reacting second-generation alkynylated graphene oxide with dimethyl azidoethylamine exhibits alkynyl characteristic peaks (3200-3300 cm⁻¹) in its infrared spectrum. -1 2150-2250cm -1 The complete disappearance of the ions proves that the reaction has been completed.

[0041] (9) Dissolve aluminum sulfate in water to prepare solutions of 100 mg / mL and 50 mg / mL. Disperse the obtained cationic modified graphene oxide in the above aluminum sulfate solution and stir for 2 hours to obtain a concentration of 2 mg / mL.

[0042] When C=50 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H]=5, ρ=2mg / mL, e=6, C=50 mg / mL, we get the range of n as 3≤n≤10.

[0043] When C = 100 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 5, ρ = 2 mg / mL, e = 6, and C = 100 mg / mL, we get the range of n as 6≤n≤20.

[0044] The results showed that, Figure 2 As shown, in a 50 mg / mL aluminum sulfate solution, n=3 cationic modified graphene oxide can exist stably, while in a 100 mg / mL aluminum sulfate solution, n=3 cationic modified graphene oxide exhibits flocculation.

[0045] Example 2 (1) 1g of graphene oxide was dispersed in 100ml of dimethylacetamide. The hydrogen ion concentration of the 0.1% aqueous dispersion of graphene oxide was 1*10. -5 Add 1 g of thionyl chloride to a solution of mol / L, stir the mixture at room temperature for 12 hours, centrifuge to remove the supernatant, and collect the precipitate. Disperse the precipitate in dimethylacetamide, then centrifuge again to precipitate, repeating the process twice. Collect the precipitate to obtain acyl-chlorographene oxide.

[0046] (2) Disperse 1g of the acyl-chlorinated graphene oxide obtained in step (1) in 100ml of dimethylacetamide, add 3g of butynol and 0.5g of triethylamine, stir and react for 4 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in dimethylacetamide, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation acyl-chlorinated graphene oxide.

[0047] (3) Disperse 1g of the acetylated graphene oxide obtained in step (2) in 100ml of dimethylacetamide, add 2g of dimethyl azidoethylamine and 0.3g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0048] (4) Disperse 1g of the tertiary amine-modified graphene oxide obtained in step (3) in 100ml of dimethylacetamide, add 0.5g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in dimethylacetamide, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the second-generation acetylated graphene oxide.

[0049] (5) Repeat steps (3) and (4) five times each to obtain cationic modified graphene oxide with 6 cations in the side chain.

[0050] (6) Dissolve aluminum sulfate in water to prepare solutions of 100 mg / mL and 50 mg / mL. Disperse the obtained cationic modified graphene oxide in the above aluminum sulfate solution and stir for 2 hours to obtain a concentration of 2 mg / mL.

[0051] When C=50 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H]=5, ρ=2mg / mL, e=6, C=50 mg / mL, we get the range of n as 3≤n≤10.

[0052] When C = 100 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 5, ρ = 2 mg / mL, e = 6, and C = 100 mg / mL, we get the range of n as 6≤n≤20.

[0053] The results showed that n=6 cationic modified graphene could exist stably in aluminum sulfate solutions of 50 mg / mL and 100 mg / mL.

[0054] Example 3 (1) 1g of graphene oxide was dispersed in 100ml of N,N-dimethylformamide. The hydrogen ion concentration of the 0.1% aqueous dispersion of graphene oxide was 0.8*10. -5 Add 1 g of thionyl chloride to a solution of mol / L, stir the mixture at room temperature for 12 hours, centrifuge to remove the supernatant, and collect the precipitate. Disperse the precipitate in N,N-dimethylformamide, then centrifuge again to precipitate. Repeat this process twice, collecting the precipitate to obtain acyl-chlorinated graphene oxide.

[0055] (2) Disperse 0.5 g of the acyl chloride graphene oxide obtained in step (1) in 100 ml of N,N-dimethylformamide, add 2 g of propynyl alcohol and 0.5 g of pyridine, stir and react for 4 hours, centrifuge to remove the supernatant and collect the precipitate. Stir the precipitate and disperse it in dimethylacetamide, then centrifuge and precipitate again. Repeat twice and collect the precipitate to obtain the first generation of acylated graphene oxide.

[0056] (3) Disperse 0.5 g of the alkynylated graphene oxide obtained in step (2) in 100 ml of N,N-dimethylformamide, add 2 g of dimethyl azidobutylamine and 0.5 g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in dimethylacetamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0057] (4) Disperse 0.5 g of the tertiary amine-modified graphene oxide obtained in step (3) in 100 ml of N,N-dimethylformamide, add 0.5 g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N,N-dimethylformamide, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the second-generation acetylated graphene oxide.

[0058] (5) Repeat steps (3) and (4) three times each to obtain cationic modified graphene oxide with four cations in the side chain.

[0059] (6) Dissolve calcium chloride in water to prepare aqueous solutions of 300 mg / mL and 80 mg / mL respectively. Add cationic modified graphene oxide to the inorganic salt solution at a concentration of 2 mg / mL and stir for 2 hours to obtain a stable dispersion.

[0060] When C = 300 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 5.09, ρ = 2 mg / mL, e = 2, and C = 300 mg / mL, we get the range of n as 5.89≤n≤19.6.

[0061] When C = 80 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 5.09, ρ = 2 mg / mL, e = 2, and C = 80 mg / mL, we get the range of n as 1.57≤n≤5.23.

[0062] The results showed that, Figure 3As shown, in a 300 mg / mL calcium chloride solution, n=4 cationic modified graphene oxide exhibits flocculation, while in an 80 mg / mL calcium chloride solution, n=4 cationic modified graphene oxide remains stable.

[0063] Example 4 (1) 1g of graphene oxide was dispersed in 100ml of N-methylpyrrolidone. The hydrogen ion concentration of the 0.1% aqueous dispersion of graphene oxide was 1.2*10. -4 Add 1 g of thionyl chloride to a solution of mol / L, stir the mixture at room temperature for 12 hours, centrifuge to remove the supernatant, and collect the precipitate. Disperse the precipitate in N-methylpyrrolidone, then centrifuge again to precipitate. Repeat this process twice, collecting the precipitate to obtain acyl-chlorographene oxide.

[0064] (2) Disperse 1g of the acyl-chlorinated graphene oxide obtained in step (1) in 100ml of N-methylpyrrolidone, add 5g of pentynyl alcohol and 0.5g of triethylamine, stir and react for 4 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N-methylpyrrolidone, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation acyl-chlorinated graphene oxide.

[0065] (3) Disperse 1g of the alkynylated graphene oxide obtained in step (2) in 100ml of N-methylpyrrolidone, add 4g of dimethyl azidooctylamine and 0.4g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in N-methylpyrrolidone, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0066] (4) Disperse 1g of the tertiary amino-modified graphene oxide obtained in step (3) in 100ml of N-methylpyrrolidone, add 1g of bromopropyne, stir and react for 2 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N-methylpyrrolidone, then centrifuge and precipitate again, repeat twice, collect the precipitate, and obtain the second-generation alkynylated graphene oxide.

[0067] (5) Repeat steps (3) and (4) seven times each to obtain cationic modified graphene oxide with 8 cations in the side chain.

[0068] (6) Dissolve calcium chloride in water to prepare aqueous solutions of 300 mg / mL and 80 mg / mL respectively. Add cationic modified graphene oxide to the inorganic salt solution at a concentration of 2 mg / mL and stir for 2 hours to obtain a stable dispersion.

[0069] When C = 300 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 3.921, ρ = 2 mg / mL, e = 2, and C = 300 mg / mL, we get the range of n as 7.65≤n≤25.5.

[0070] When C = 80 mg / mL, according to the formula C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; substituting -lg[H] = 3.921, ρ = 2 mg / mL, e = 2, and C = 80 mg / mL, we get the range of n as 2.04≤n≤6.8.

[0071] The results showed that, Figure 3 As shown, n=8 cationic modified graphene oxide is stable in a 300 mg / mL calcium chloride solution. However, in an 80 mg / mL calcium chloride solution, n=8 cationic modified graphene oxide exhibits flocculation.

[0072] Example 5 (1) Disperse 0.1g of graphene oxide in 100ml of N-methylpyrrolidone, add 0.1g of thionyl chloride, stir and react at room temperature for 4 hours, centrifuge to remove the supernatant and collect the precipitate. Stir the precipitate and disperse it in N-methylpyrrolidone, then centrifuge again to precipitate, repeat twice, collect the precipitate to obtain acyl-chlorinated graphene oxide.

[0073] (2) Disperse 1g of the acyl-chlorinated graphene oxide obtained in step (1) in 100ml of N-methylpyrrolidone, add 5g of pentynyl alcohol and 1g of triethylamine, stir and react for 12 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N-methylpyrrolidone, then centrifuge and precipitate again, repeat twice, collect the precipitate, and obtain the first-generation acyl-chlorinated graphene oxide.

[0074] (3) Disperse 1g of the alkynylated graphene oxide obtained in step (2) in 100ml of N-methylpyrrolidone, add 5g of dimethyl azidooctylamine and 3g of cuprous bromide, stir and react for 4 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in N-methylpyrrolidone, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0075] (4) Disperse 1g of the tertiary amino-modified graphene oxide obtained in step (3) in 100ml of N-methylpyrrolidone, add 5g of bromopropyne, stir and react for 12 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N-methylpyrrolidone, then centrifuge and precipitate again, repeat twice, collect the precipitate, and obtain the second-generation alkynylated graphene oxide.

[0076] (5) Repeat steps (3) and (4) three times each to obtain cationic modified graphene with four cations in the side chain.

[0077] (6) Dissolve aluminum sulfate in water to prepare a solution of 50 mg / mL, disperse the obtained cationic modified graphene oxide in the above aluminum sulfate solution, stir for 2 hours, and the concentration is 2 mg / mL.

[0078] A stable, dispersed modified graphene dispersion containing a high concentration of salt was obtained, and no aggregation occurred after shaking and standing for 12 hours.

[0079] Example 6 (1) Disperse 2g of graphene oxide in 100ml of N-methylpyrrolidone, add 2g of thionyl chloride, stir and react at room temperature for 12 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in N-methylpyrrolidone, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain acyl-chlorinated graphene oxide.

[0080] (2) Disperse 1g of the acyl-chlorinated graphene oxide obtained in step (1) in 100ml of N-methylpyrrolidone, add 10g of pentynyl alcohol and 0.5g of triethylamine, stir and react for 4 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir the precipitate and disperse it in N-methylpyrrolidone, then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation acyl-chlorinated graphene oxide.

[0081] (3) Disperse 1g of the alkynylated graphene oxide obtained in step (2) in 100ml of N-methylpyrrolidone, add 10g of dimethyl azidooctylamine and 0.5g of cuprous bromide, stir and react for 2 hours under inert gas protection, remove the supernatant after centrifugation, and collect the precipitate. Disperse the precipitate in N-methylpyrrolidone, and then centrifuge and precipitate again. Repeat twice, collect the precipitate, and obtain the first-generation tertiary amine-modified graphene oxide.

[0082] (4) Disperse 1g of the tertiary amino-modified graphene oxide obtained in step (3) in 100ml of N-methylpyrrolidone, add 10g of bromopropyne, stir and react for 6 hours, centrifuge and remove the supernatant, and collect the precipitate. Stir and disperse the precipitate in N-methylpyrrolidone, then centrifuge and precipitate again, repeat twice, collect the precipitate, and obtain the second-generation alkynylated graphene oxide.

[0083] (5) Repeat steps (3) and (4) four times each to obtain cationic modified graphene with five cations in the side chain.

[0084] (6) Dissolve aluminum sulfate in water to prepare a solution of 50 mg / mL, disperse the obtained cationic modified graphene oxide in the above aluminum sulfate solution, stir for 2 hours, and the concentration is 2 mg / mL.

[0085] A stable, dispersed modified graphene dispersion containing a high concentration of salt was obtained, and no aggregation occurred after shaking and standing for 12 hours.

[0086] The above embodiments describe in detail the structure, features, and effects of the present invention. The above description is only a preferred embodiment of the present invention. Any changes made in accordance with the concept of the present invention, or equivalent embodiments modified to have equivalent changes, shall still fall within the scope of protection of the present invention if they do not exceed the scope covered by the specification.

Claims

1. A modified graphene dispersion containing a high concentration of salt, characterized in that, Composed of cationic modified graphene oxide, inorganic salts, and water, the cationic modified graphene oxide contains side chains with a controllable number of cations, and the controllable number n of cations on a single side chain satisfies the following constraint: C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; Where C is the concentration of inorganic salt, [H] is the hydrogen ion concentration in a 0.1 wt% aqueous solution of unmodified graphene oxide, e is the total charge of inorganic salt cations, and ρ is the concentration of modified graphene.

2. A method for preparing the modified graphene dispersion as described in claim 1, characterized in that, It includes the following steps: (1) Disperse graphene oxide in a solvent, add excess thionyl chloride, stir and react for 4-12 hours, centrifuge and remove the supernatant to obtain acyl-chlorinated graphene oxide; the mass ratio of thionyl chloride to graphene oxide is not less than 1:

1. (2) Disperse the acyl chloride graphene oxide obtained in step (1) in a solvent, add hydroxy-alkynyl compound and acid-binding agent, stir and react for 4-12 hours, remove the supernatant after centrifugation, and obtain alkynylated graphene oxide; the mass ratio of acyl chloride graphene oxide, hydroxy-alkynyl compound and acid-binding agent is 1-20:5-200:1-10. (3) Disperse the alkynylated graphene oxide obtained in step (2) in a solvent, add an azide-amine compound and a copper catalyst, stir and react under inert gas protection, collect the precipitate after centrifugation, and obtain tertiary amine-modified graphene oxide; the mass ratio of the alkynylated graphene oxide, the azide-amine compound and the copper catalyst is 1-20:5-200:3-10; (4) Disperse the tertiary amino-modified graphene oxide obtained in step (3) in a solvent, add bromopropyne, stir for 2-12 hours, collect the precipitate after centrifugation, and obtain alkynyl-modified graphene oxide; the mass ratio of the tertiary amino-modified graphene oxide to bromopropyne is 1-20:5-200. (5) Repeat steps (3) and (4) to obtain cationic modified graphene oxide; (6) Dissolve the inorganic salt in a solvent to form an inorganic salt solution, and disperse the cationic modified graphene oxide obtained in step (5) in the inorganic salt solution to obtain a modified graphene dispersion containing a high concentration of salt. The concentration C of the inorganic salt and the number n of cations on the cationic modified graphene oxide satisfy the following formula: C*e / {10*(-lg[H])*ρ}≤n≤C*e / {3*(-lg[H])*ρ}; Where C is the concentration of inorganic salt, [H] is the hydrogen ion concentration in a 0.1 wt% aqueous solution of unmodified graphene oxide, e is the total charge of inorganic salt cations, and ρ is the concentration of modified graphene.

3. The method according to claim 2, characterized in that, The solvent is water, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, or a mixture of the above solvents in any proportion.

4. The preparation method according to claim 2, characterized in that, The hydroxy-alkynyl compound in step (2) is selected from ethynyl alcohol, propynyl alcohol, butynyl alcohol, penynyl alcohol, hexynyl alcohol, hepynyl alcohol, octyynyl alcohol, or homologues whose main chain contains more methylene groups.

5. The preparation method according to claim 2, characterized in that, The acid-binding agent mentioned in step (2) is selected from pyridine, triethylamine, and dimethylaminopyridine.

6. The preparation method according to claim 2, characterized in that, The azido-amine compound in step (3) is selected from dimethylazidoethylamine, dimethylazidopropylamine, dimethylazidobutylamine, dimethylazidopentylamine, dimethylazidohexylamine, dimethylazidoheptylamine, dimethylazidooctylamine, or homologues with more methylene groups in the main chain.

7. The preparation method according to claim 2, characterized in that, The copper catalyst mentioned in step (3) is selected from cuprous chloride, cuprous bromide, and elemental copper.

8. The preparation method according to claim 2, characterized in that, The concentrations of graphene oxide in step (1), acyl chloride graphene oxide in step (2), alkynylated graphene oxide in step (3), and tertiary amine-modified graphene oxide in step (4) are 1-20 mg / mL.

9. The preparation method according to claim 2, characterized in that, The cations of the inorganic salt are selected from aluminum ions, calcium ions, sodium ions, and potassium ions; the anions are selected from sulfate ions, chloride ions, and nitrate ions.

10. The application of a modified graphene dispersion containing a high concentration of salt as described in claim 1.

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