Preparation method of modified graphene, modified graphene prepared by method and dispersion system of modified graphene

Abstract

The invention provides a preparation method of modified graphene, the modified graphene prepared by the method and a dispersion system. The method comprises the following steps: step 1, mixing graphene oxide and diisocyanate for reaction to obtain a product A; and 2, reacting the product A with methoxypolyethylene glycol to obtain the modified graphene. The graphene obtained by the method can be uniformly and stably dispersed in the solvent.

Description

Technical Field

[0001] The present invention relates to the technical field of graphene materials, and more particularly to a method for preparing modified graphene, the modified graphene prepared by the method, and a dispersion system prepared by the modified graphene. Background Art

[0002] Graphene is a two-dimensional nanostructured carbon material with a unique atomic structure, excellent conductivity and high specific surface area, and excellent mechanical, thermal, electrical and optical properties. Therefore, it has a wide range of applications in optoelectronic materials, environmental protection, electronic equipment and biomedicine.

[0003] Graphene is used in the form of a dispersion in many applications. In order to stably disperse graphene in the medium, usually, a stabilizing surfactant, polymer or other stabilizing substance is added to the dispersion medium of graphene to achieve stable dispersion of graphene in the dispersion medium.

[0004] Chinese patent CN109896521A discloses a stable graphene dispersion and a preparation method thereof. The added macromolecular polymer can be linked to the graphene through π-π bonds, so that the graphene is stably dispersed in the aqueous solution.

[0005] Chinese patent CN110330012A discloses a method for preparing a high-concentration graphene aqueous dispersion and a self-dispersed graphene powder. By adding potassium carboxymethyl cellulose to an aqueous solution of an inorganic salt, stable dispersion of graphene can be achieved.

[0006] Chinese patent CN110655596A discloses a star-shaped cationic graphene dispersant and its application, which uses a star-shaped cationic dispersant to achieve dispersion of graphene in a solvent.

[0007] However, the added substances will affect some physical properties of graphene, and many substances will migrate or escape into the environment after the dispersion medium is removed, causing pollution to the material itself or the environment. Summary of the invention

[0008] In order to solve the above problems, the present invention provides a method for preparing modified graphene, which can disperse graphene in a solvent uniformly and stably.

[0009] First, one of the purposes of the present invention is to provide a method for preparing modified graphene, comprising the following steps:

[0010] Step 1: mixing graphene oxide and diisocyanate to obtain product A;

[0011] Step 2: react product A with polyethylene glycol monomethyl ether to obtain modified graphene.

[0012] Preferably, graphene oxide and polyethylene glycol monomethyl ether need to be pretreated before the reaction, wherein the pretreatment method is: drying graphene oxide or polyethylene glycol monomethyl ether at a pressure of -0.09 to -0.05 MPa.G and a temperature of 80 to 200°C for 6 to 24 hours. The present application pretreats graphene oxide and polyethylene glycol monomethyl ether before the reaction, ensuring that the hydroxyl groups contained on the surface of graphene oxide can fully react with isocyanate, and ensuring that polyethylene glycol monomethyl ether can be fully grafted to the surface of graphene.

[0013] Preferably, in step one, graphene oxide is first dissolved in solvent A and subjected to ultrasonic treatment, and then diisocyanate is added and ultrasonic treatment is continued to obtain product A by reaction.

[0014] More preferably, in step 1, graphene oxide is dissolved in solvent A and first subjected to ultrasonic treatment for 15 to 60 minutes; then diisocyanate is added and ultrasonic treatment is continued for 15 to 60 minutes.

[0015] Preferably, the diisocyanate is diphenylmethane diisocyanate or hexamethylene diisocyanate.

[0016] Preferably, in step 1, solvent A is an organic solvent; preferably one of dry acetone, butanone, and tetrahydrofuran; wherein anhydrous magnesium chloride or anhydrous magnesium sulfate can be used as a desiccant for solvent A; the drying method for solvent A is: adding 30 to 50% of the desiccant to solvent A, and drying at room temperature for 6 to 24 hours.

[0017] Preferably, in step 1, graphene oxide and diisocyanate are mixed and reacted at a temperature of 10 to 50° C. for 6 to 24 hours to obtain product A. The reaction temperature and time refer to the temperature and time of the reaction after ultrasonic treatment.

[0018] Preferably, in step 1, product A is obtained by the following method: first, 90-95% of solvent A is evaporated, and the remaining substance is dried at a pressure of -0.09 to -0.05 MPa.G and a temperature of 80 to 200°C for 6 to 24 hours to obtain product A.

[0019] Preferably, in step 1, the mass ratio of the added diisocyanate to the graphene oxide is 2 to 4.2:1; the mass ratio of the added solvent A to the graphene oxide is 50 to 100:1.

[0020] Preferably, in step 2, product A is dissolved in solvent A and subjected to ultrasonic treatment, and then polyethylene glycol monomethyl ether is added and subjected to ultrasonic treatment to obtain modified graphene.

[0021] More preferably, in step 2, product A is first dissolved in solvent A and subjected to ultrasonic treatment for 15 to 60 minutes; polyethylene glycol monomethyl ether is then added and the ultrasonic treatment is continued for 15 to 60 minutes.

[0022] Preferably, in step 2, solvent A is an organic solvent; preferably one of dry acetone, butanone, and tetrahydrofuran; wherein anhydrous magnesium chloride or anhydrous magnesium sulfate can be used as a desiccant for solvent A; the drying method for solvent A is: adding 30 to 50% of the desiccant to solvent A, and drying at room temperature for 6 to 24 hours.

[0023] Preferably, in step 2, product A is mixed with polyethylene glycol monomethyl ether and reacted at 10 to 50° C. for 6 to 24 hours to obtain modified graphene. The reaction temperature and time refer to the temperature and time of the reaction after ultrasonic treatment.

[0024] Preferably, in step 2, the modified graphene is obtained by the following method: firstly, 90-95% of the solvent A is evaporated, the remaining substance is dissolved in ether and stirred sufficiently, and then filtered through a 2-6 um sand core funnel to obtain the modified graphene.

[0025] Preferably, in step 2, the mass ratio of the added polyethylene glycol monomethyl ether to the graphene oxide in step 1 is 1 to 5:1; the mass ratio of the added solvent to the graphene oxide in step 1 is 50 to 200:1.

[0026] Preferably, in step 2, the molecular weight of polyethylene glycol monomethyl ether is 200 to 20,000 g / mol; preferably 200 to 10,000 g / mol.

[0027] Secondly, the second object of the present invention is to provide a modified graphene obtained by the preparation method of one of the objects of the present invention.

[0028] Again, the third object of the present invention is to provide a dispersion system of modified graphene obtained by the second object of the present invention, wherein the dispersion system is obtained by dispersing the modified graphene in solvent B.

[0029] Preferably, the solvent B is one or a combination of acetone, methanol and ethanol.

[0030] The dispersion mass concentration of graphene oxide in solvent B is 1-10%, and can be stably maintained for more than 60 days without sedimentation.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention allows the hydroxyl groups on the surface of graphene oxide to react with isocyanate, so that highly active isocyanate functional groups (NCO) are grafted onto the surface of graphene oxide, and the second most active NCO functional groups react with the hydroxyl groups of polyvinyl alcohol monomethyl ether, so that the graphene oxide carries polyvinyl alcohol segments, so that the graphene oxide is efficiently dispersed in the solvent, and the dispersion performance of the graphene in the solvent is not affected by the addition of substances and changes in concentration.

[0033] 2. The present invention uses polyethylene glycol monomethyl ether with a molecular weight of 200 to 20,000 g / mol to be grafted onto the surface of graphene oxide, so that the graphene oxide is better dispersed in the solvent and the viscosity of the dispersion system is maintained within a reasonable range.

[0034] 3. The dispersion system provided by the present invention has good stability, which overcomes the impact of the migration or dissipation of the added substances into the environment on the material itself or the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a TEM image of the modified graphene material prepared in Example 1 of the present invention.

[0036] Figure 2 This is the infrared spectrum of the modified graphene material obtained in Example 1 of the present invention. DETAILED DESCRIPTION

[0037] The present invention is described in detail below in conjunction with specific drawings and embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention still fall within the scope of protection of the present invention.

[0038] In the present invention, the raw materials and reagents used are commercially available unless otherwise specified.

[0039] Example 1

[0040] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0041] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of diphenylmethane diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 30°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0042] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether with a molecular weight of 1000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30°C for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0043] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0044] Figure 1 This is a TEM image of the modified graphene material obtained in this embodiment. It can be seen from the figure that the modified graphene oxide is a single layer without obvious stacking, indicating that the modified graphene has good dispersion.

[0045] Figure 2 This is the infrared spectrum of the modified graphene material obtained in this example. It can be seen from the figure that the product contains polyethylene glycol-related structures, indicating that polyethylene glycol is grafted onto the surface of graphene oxide.

[0046] Example 2

[0047] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 100° C. for 20 h under a pressure of -0.06 MPa.G. Anhydrous magnesium sulfate of 50% by weight was added to acetone and dried at room temperature for 24 h.

[0048] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 15min. 3g of hexamethylene diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 40min. The reaction was carried out at 20°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0049] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 40 min. 3 g of polyethylene glycol monomethyl ether with a molecular weight of 1000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 40 min. The reaction was carried out at 30°C for 20 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0050] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0051] Example 3

[0052] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 150° C. for 12 h under a pressure of -0.08 MPa.G. Anhydrous magnesium chloride of 35% by weight was added to acetone and dried at room temperature for 24 h.

[0053] 1g of graphene oxide after drying was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 20min. 3.5g of diphenylmethane diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 40°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 150°C for 18h at a pressure of -0.07MPa.G.

[0054] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 50 min. 3.5 g of polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 40 min. The reaction was carried out at 40°C for 15 h. 90% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0055] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0056] Example 4

[0057] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 150° C. for 12 h under a pressure of -0.08 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to tetrahydrofuran and dried at room temperature for 24 h.

[0058] 1g of dried graphene oxide was dissolved in 150mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30min. 4g of hexamethylene diisocyanate was dissolved in the above 150mL of tetrahydrofuran solution and ultrasonically dispersed for 30min. The mixture was reacted at 40°C for 24h. 95% of the tetrahydrofuran was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0059] The dried material was redissolved in 150 mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30 min. 4 g of polyethylene glycol monomethyl ether with a molecular weight of 500 g / mol was dissolved in the above 150 mL of tetrahydrofuran solution and ultrasonically dispersed for 30 min. The mixture was reacted at 30° C. for 24 h. 95% of the tetrahydrofuran was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sand core funnel to obtain a solid material.

[0060] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0061] Example 5

[0062] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium chloride was added to acetone and dried at room temperature for 24 h.

[0063] 1g of graphene oxide after drying was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of diphenylmethane diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 50°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 180°C for 15h at a pressure of -0.06MPa.G.

[0064] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether with a molecular weight of 5000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 50° C. for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sand core funnel to obtain a solid material.

[0065] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0066] Example 6

[0067] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0068] 1g of dried graphene oxide was dissolved in 80mL of dry acetone solution and ultrasonically dispersed for 50min. 2.5g of hexamethyl diisocyanate was dissolved in the above 80mL of acetone solution and ultrasonically dispersed for 40min. The mixture was reacted at 50°C for 18h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0069] The dried material was redissolved in 100 mL of acetone solution dried with anhydrous magnesium chloride, and ultrasonically dispersed for 40 min. 5 g of polyethylene glycol monomethyl ether with a molecular weight of 5000 g / mol was dissolved in the above 100 mL of acetone solution, and ultrasonically dispersed for 40 min. The reaction was carried out at 50°C for 15 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2um sand core funnel to obtain a solid material.

[0070] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0071] Example 7

[0072] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0073] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of diphenylmethane diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 30°C for 20h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0074] The dried material was redissolved in 200 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether with a molecular weight of 20,000 g / mol was dissolved in the above 200 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 40°C for 15 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0075] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0076] Example 8

[0077] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0078] 1g of dried graphene oxide was dissolved in 150mL of dry acetone solution and ultrasonically dispersed for 30min. 4g of hexamethyl diisocyanate was dissolved in the above 150mL of acetone solution and ultrasonically dispersed for 30min. The mixture was reacted at 30°C for 20h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0079] The dried material was redissolved in 180 mL of dry acetone solution and ultrasonically dispersed for 30 min. 4 g of polyethylene glycol monomethyl ether with a molecular weight of 20,000 g / mol was dissolved in the above 180 mL of acetone solution and ultrasonically dispersed for 30 min. The mixture was reacted at 30° C. for 20 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sand core funnel to obtain a solid material.

[0080] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0081] Example 9

[0082] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to tetrahydrofuran and dried at room temperature for 24 h.

[0083] 1g of dried graphene oxide was dissolved in 60mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30min. 2g of diphenylmethane diisocyanate was dissolved in the above 60mL of tetrahydrofuran solution and ultrasonically dispersed for 30min. The mixture was reacted at 30°C for 24h. 95% of the tetrahydrofuran was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0084] The dried material was redissolved in 80 mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30 min. 1.5 g of polyethylene glycol monomethyl ether with a molecular weight of 10,000 g / mol was dissolved in the above 80 mL of tetrahydrofuran solution and ultrasonically dispersed for 30 min. The mixture was reacted at 30° C. for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sand core funnel to obtain a solid material.

[0085] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 10%. The dispersion still did not produce sedimentation after 60 days.

[0086] Example 10

[0087] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0088] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of hexamethyl diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The mixture was reacted at 30°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0089] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether with a molecular weight of 10,000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30°C for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0090] Without adding any other additives, the solid matter was redispersed in ethanol at a concentration of 10%. The dispersion still did not produce sedimentation after 60 days.

[0091] Embodiment 11

[0092] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 150° C. for 12 h under a pressure of -0.08 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0093] 1g of dried graphene oxide was dissolved in 120mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of diphenylmethane diisocyanate was dissolved in the above 120mL of acetone solution and ultrasonically dispersed for 30min. The mixture was reacted at 40°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0094] The dried material was redissolved in 150 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2.5 g of polyethylene glycol monomethyl ether with a molecular weight of 200 g / mol was dissolved in the above 150 mL of acetone solution and ultrasonically dispersed for 30 min. The mixture was reacted at 30° C. for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sand core funnel to obtain a solid material.

[0095] Without adding any other additives, the solid matter was redispersed in methanol at a concentration of 5%. The dispersion still did not produce sedimentation after 60 days.

[0096] Example 12

[0097] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 150° C. for 12 h under a pressure of -0.08 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0098] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of hexamethylene diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 40°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0099] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether with a molecular weight of 2000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30°C for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0100] Without adding any other additives, the solid matter was redispersed in acetone at a concentration of 5%. The dispersion still did not settle after 60 days.

[0101] Comparative Example 1

[0102] The raw materials of polyethylene glycol monomethyl ether and graphene oxide were dried at 120° C. for 8 h under a pressure of -0.09 MPa.G. 40% by weight of anhydrous magnesium sulfate was added to acetone and dried at room temperature for 24 h.

[0103] 1g of dried graphene oxide was dissolved in 100mL of dry acetone solution and ultrasonically dispersed for 30min. 2.5g of diphenylmethane diisocyanate was dissolved in the above 100mL of acetone solution and ultrasonically dispersed for 30min. The reaction was carried out at 30°C for 24h. 95% of the acetone was evaporated by rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 120°C for 24h at a pressure of -0.09MPa.G.

[0104] The dried material was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether with a molecular weight of 25000 g / mol was dissolved in the above 100 mL of acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30°C for 24 h. 95% of the acetone was evaporated by a rotary evaporator, and the remaining material was dissolved in 100 mL of ether, stirred at 200 rpm for 30 min, and filtered through a 2 um sand core funnel to obtain a solid material.

[0105] Without any other additives, the solid matter was redispersed in ethanol at a concentration of 5%. The dispersion settled within 30 days.

Claims

1. A method for preparing modified graphene, characterized in that: The method comprises the following steps: Step 1: mixing graphene oxide and diisocyanate to obtain product A; Step 2: react product A with polyethylene glycol monomethyl ether to obtain modified graphene.

2. The method for preparing modified graphene according to claim 1, characterized in that, The graphene oxide and polyethylene glycol monomethyl ether are pretreated before the reaction, and the pretreatment method comprises the following steps: The graphene oxide or polyethylene glycol monomethyl ether is dried at a pressure of -0.09 to -0.05 MPa.G and a temperature of 80 to 200° C. for 6 to 24 hours.

3. The method for preparing modified graphene according to claim 1, characterized in that, In the step 1, the graphene oxide is first dissolved in solvent A and subjected to ultrasonic treatment, and then diisocyanate is added and ultrasonic treatment is continued to obtain product A; Preferably, the graphene oxide is dissolved in solvent A and ultrasonically treated for 15 to 60 minutes; then diisocyanate is added and ultrasonically treated for another 15 to 60 minutes.

4. The method for preparing modified graphene according to claim 3, characterized in that, In the step 1, the reaction temperature is 10 to 50° C. and the reaction time is 6 to 24 hours.

5. The method for preparing modified graphene according to claim 3, characterized in that, In the step 1, product A is obtained by the following method: First, 90-95% of the solvent A is evaporated, and the remaining material is dried at a pressure of -0.09 to -0.05 MPa.G and a temperature of 80 to 200°C for 6 to 24 hours to obtain product A.

6. The method for preparing modified graphene according to claim 3, characterized in that: In the step 1, the mass ratio of the added diisocyanate to the graphene oxide is 2 to 4.2:1; The mass ratio of the added solvent A to the graphene oxide is 50-100:1; The diisocyanate is diphenylmethane diisocyanate or hexamethylene diisocyanate.

7. The method for preparing modified graphene according to claim 1, characterized in that: In the step 2, the product A is dissolved in solvent A and subjected to ultrasonic treatment, and then polyethylene glycol monomethyl ether is added and subjected to ultrasonic treatment to obtain modified graphene; Preferably, the product A is first dissolved in solvent A and subjected to ultrasonic treatment for 15 to 60 minutes; polyethylene glycol monomethyl ether is then added and the ultrasonic treatment is continued for 15 to 60 minutes.

8. The method for preparing modified graphene according to claim 7, characterized in that: In the step 2, the reaction temperature is 10 to 50° C. and the reaction time is 6 to 24 hours.

9. The method for preparing modified graphene according to claim 7, characterized in that: In the step 2, the modified graphene is obtained by the following method: First, 90-95% of the solvent A is evaporated, and the remaining substance is dissolved in ether and stirred sufficiently, and then filtered to obtain the modified graphene.

10. The method for preparing modified graphene according to claim 7, characterized in that: In the step 2, the mass ratio of the added polyethylene glycol monomethyl ether to the graphene oxide is 1 to 5:1; The mass ratio of the added solvent A to the graphene oxide is 50-200:1; The molecular weight of the polyethylene glycol monomethyl ether is 200 to 20,000 g / mol, preferably 200 to 10,000 g / mol.

11. The method for preparing modified graphene according to claim 3 or 7, characterized in that: In step 1 or step 2, the solvent A is an organic solvent; Preferably, the organic solvent is one of dry acetone, butanone, and tetrahydrofuran; Preferably, the desiccant of the solvent A is one or a combination of anhydrous magnesium chloride and anhydrous magnesium sulfate; Preferably, the drying method in the solvent A is: adding 30 to 50% of a desiccant into the solvent A, and drying at room temperature for 6 to 24 hours.

12. A modified graphene, characterized in that: The method is obtained by any one of claims 1 to 11.

13. A dispersion system of modified graphene, characterized in that: The modified graphene of claim 12 is dispersed in solvent B; Preferably, the solvent B is one or a combination of acetone, methanol and ethanol.

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