A method for preparing modified graphene, the modified graphene obtained by the method, and its dispersion system.

Abstract

The application provides a preparation method of modified graphene, modified graphene prepared by the method and a dispersion system. The method comprises the following steps: in step one, graphene oxide is mixed with diisocyanate to obtain product A; in step two, product A is reacted with polyethylene glycol monomethyl ether to obtain modified graphene. The graphene obtained by the method can be uniformly and stably dispersed in a solvent.

Description

Technical Field

[0001] This invention relates to the field of graphene materials technology, and more specifically, to a method for preparing modified graphene, the modified graphene obtained by the method, and a dispersion system obtained from the modified graphene. Background Technology

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

[0003] Graphene is often used in the form of dispersions. To ensure that graphene is stably dispersed in a medium, surfactants, polymers, or other stabilizing substances with stabilizing effects are usually added to the dispersion medium.

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

[0005] Chinese patent CN110330012A discloses a method for preparing a high-concentration aqueous graphene dispersion and a self-dispersing graphene powder. By adding potassium carboxymethyl cellulose to an aqueous solution of inorganic salts, 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 disperse graphene in a solvent.

[0007] However, added substances can affect some of the physical properties of graphene, and many of these substances can 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] To address the above problems, this invention provides a method for preparing modified graphene, which can uniformly and stably disperse graphene in a solvent.

[0009] Firstly, one of the objectives of this invention is to provide a method for preparing modified graphene, comprising the following steps:

[0010] Step 1: Mix graphene oxide with diisocyanate and react 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 require pretreatment before the reaction. The pretreatment method involves drying the 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. This application pretreatment of graphene oxide and polyethylene glycol monomethyl ether before the reaction ensures that the hydroxyl groups on the surface of graphene oxide can fully react with the isocyanate and that polyethylene glycol monomethyl ether can be fully grafted onto the surface of graphene.

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

[0014] More preferably, in step one, graphene oxide is dissolved in solvent A and ultrasonically treated for 15-60 min; then diisocyanate is added and ultrasonic treatment is continued for 15-60 min.

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

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

[0017] Preferably, in step one, after mixing graphene oxide and diisocyanate, the mixture is reacted at a temperature of 10–50°C for 6–24 hours to obtain product A. The reaction temperature and time refer to the temperature and time at which the reaction takes place after ultrasonic treatment.

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

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

[0020] Preferably, in step two, after product A is dissolved in solvent A and ultrasonically treated, polyethylene glycol monomethyl ether is added and ultrasonic treatment is continued to obtain modified graphene.

[0021] More preferably, in step two, product A is first dissolved in solvent A and ultrasonically treated for 15-60 min; then polyethylene glycol monomethyl ether is added and ultrasonic treatment is continued for 15-60 min.

[0022] Preferably, in step two, solvent A is an organic solvent; preferably, it is one of dried acetone, butanone, or tetrahydrofuran; wherein, anhydrous magnesium chloride or anhydrous magnesium sulfate can be used as the drying agent for solvent A; the drying method for solvent A is as follows: 30-50% of the drying agent is added to solvent A and dried at room temperature for 6-24 hours.

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

[0024] Preferably, in step two, the modified graphene is obtained by the following method: first, 90-95% of solvent A is distilled off, the remaining substance is dissolved in diethyl ether and stirred thoroughly, and then filtered through a 2-6 μm sand core funnel to obtain the modified graphene.

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

[0026] Preferably, in step two, the molecular weight of polyethylene glycol monomethyl ether is 200–20000 g / mol; more preferably, it is 200–10000 g / mol.

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

[0028] Furthermore, a third objective of this invention is to provide a dispersion system of modified graphene according to the second objective of this invention, wherein the dispersion system is obtained by dispersing the modified graphene in solvent B.

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

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

[0031] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0032] 1. This invention involves reacting hydroxyl groups on the surface of graphene oxide with isocyanates to graft highly active isocyanate functional groups (NCO) onto the surface of graphene oxide. The second most active NCO functional groups react with the hydroxyl groups of polyvinyl alcohol monomethyl ether, thereby giving the graphene oxide polyvinyl alcohol segments. This allows the graphene oxide to be efficiently dispersed in the solvent, and the dispersion performance of the graphene in the solvent will not be affected by the addition of external substances or changes in concentration.

[0033] 2. This invention uses polyethylene glycol monomethyl ether with a molecular weight of 200 to 20000 g / mol to graft onto the surface of graphene oxide, so that graphene oxide can be better dispersed in the solvent and the viscosity of the dispersion system can be kept within a reasonable range.

[0034] 3. The dispersion system provided by this invention has good stability and overcomes the impact of the migration or escape of added substances into the environment on the material itself or the environment. Attached Figure Description

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

[0036] Figure 2 The image shows the infrared spectrum of the modified graphene material prepared in Example 1 of this invention. Detailed Implementation

[0037] The present invention will now be described in detail with reference to the accompanying drawings and embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0038] Unless otherwise specified, all raw materials and reagents used in this invention are commercially available.

[0039] Example 1

[0040] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0042] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether (molecular weight 1000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0043] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

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

[0045] Figure 2 The image shows the infrared spectrum of the modified graphene material prepared in this embodiment. As can be seen from the image, the product contains polyethylene glycol-related structures, indicating that polyethylene glycol is grafted onto the surface of graphene oxide.

[0046] Example 2

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

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

[0049] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 40 min. 3 g of polyethylene glycol monomethyl ether (molecular weight 1000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0050] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0051] Example 3

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

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

[0054] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 50 min. 3.5 g of polyethylene glycol monomethyl ether (molecular weight 500 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0055] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0056] Example 4

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

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

[0059] The dried substance was redissolved in 150 mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30 min. 4 g of polyethylene glycol monomethyl ether (molecular weight 500 g / mol) was dissolved in the same 150 mL tetrahydrofuran solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30 °C for 24 h. 95% of the tetrahydrofuran was distilled off using a rotary evaporator. The remaining substance was dissolved in 100 mL of diethyl ether, stirred at 200 rpm for 30 min, and filtered through a 2 μm sintered glass funnel to obtain a solid.

[0060] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0061] Example 5

[0062] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium chloride (40% by mass) was added to acetone and dried at room temperature for 24 hours.

[0063] 1 g of dried graphene oxide was dissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2.5 g of diphenylmethane diisocyanate was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining material was placed in a vacuum drying oven and dried at 180 °C for 15 h under a pressure of -0.06 MPa.G.

[0064] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether (molecular weight 5000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0065] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0066] Example 6

[0067] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0069] The dried substance was redissolved in 100 mL of anhydrous magnesium chloride-dried acetone solution and ultrasonically dispersed for 40 min. 5 g of polyethylene glycol monomethyl ether (molecular weight 5000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether and stirred at 200 rpm for 30 min. The mixture was then filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0070] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0071] Example 7

[0072] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0074] The dried substance was redissolved in 200 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether (molecular weight 20000 g / mol) was dissolved in the same 200 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0075] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0076] Example 8

[0077] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0079] The dried substance was redissolved in 180 mL of dry acetone solution and ultrasonically dispersed for 30 min. 4 g of polyethylene glycol monomethyl ether (molecular weight 20000 g / mol) was dissolved in the same 180 mL acetone solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30 °C for 20 h. 95% of the acetone was evaporated using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0080] Without the addition of any other additives, the solids were redispersed in ethanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0081] Example 9

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

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

[0084] The dried substance was redissolved in 80 mL of dry tetrahydrofuran solution and ultrasonically dispersed for 30 min. 1.5 g of polyethylene glycol monomethyl ether (molecular weight 10000 g / mol) was dissolved in the same 80 mL tetrahydrofuran solution and ultrasonically dispersed for 30 min. The reaction was carried out at 30 °C for 24 h. 95% of the acetone was evaporated using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0085] Without the addition of any other additives, the solid substance was redispersed in ethanol at a concentration of 10%. The dispersion did not settle after 60 days.

[0086] Example 10

[0087] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0089] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 5 g of polyethylene glycol monomethyl ether (molecular weight 10000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0090] Without the addition of any other additives, the solid substance was redispersed in ethanol at a concentration of 10%. The dispersion did not settle after 60 days.

[0091] Example 11

[0092] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 150°C for 12 hours under a pressure of -0.08 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0094] The dried substance was redissolved in 150 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2.5 g of polyethylene glycol monomethyl ether (molecular weight 200 g / mol) was dissolved in the same 150 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0095] Without the addition of any other additives, the solids were redispersed in methanol at a concentration of 5%. The dispersion did not settle after 60 days.

[0096] Example 12

[0097] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 150°C for 12 hours under a pressure of -0.08 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0099] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether (molecular weight 2000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

[0100] Without the addition of any other additives, the solids were redispersed in acetone at a concentration of 5%. The dispersion did not settle after 60 days.

[0101] Comparative Example 1

[0102] Polyethylene glycol monomethyl ether and graphene oxide raw materials were dried at 120°C for 8 hours under a pressure of -0.09 MPa.G. Anhydrous magnesium sulfate (40% by mass) was added to acetone and dried at room temperature for 24 hours.

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

[0104] The dried substance was redissolved in 100 mL of dry acetone solution and ultrasonically dispersed for 30 min. 2 g of polyethylene glycol monomethyl ether (molecular weight 25000 g / mol) was dissolved in the same 100 mL 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 using a rotary evaporator, and the remaining substance was dissolved in 100 mL of diethyl ether. The mixture was stirred at 200 rpm for 30 min and filtered through a 2 μm sintered glass funnel to obtain a solid substance.

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

Claims

1. A method for preparing modified graphene, characterized by, The method comprises the following steps: Step one, mixing and reacting graphene oxide with diisocyanate to obtain product A; Step two, reacting product A with polyethylene glycol monomethyl ether to obtain modified graphene.

2. The method of claim 1, wherein the modified graphene is prepared by the steps of: The graphene oxide and polyethylene glycol monomethyl ether are pretreated before 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~-0.05 MPa.G and a temperature of 80~200℃ for 6~24h.

3. The method for preparing modified graphene according to claim 1, wherein in the step one, the graphene oxide is first dissolved in solvent A and subjected to ultrasonic treatment, then diisocyanate is added and subjected to ultrasonic treatment, and product A is obtained through reaction.

4. The method for preparing modified graphene according to claim 3, wherein the graphene oxide is dissolved in solvent A and subjected to ultrasonic treatment for 15~60min; then diisocyanate is added and subjected to ultrasonic treatment for 15~60min.

5. The method for preparing modified graphene according to claim 3, wherein in the step one, the reaction temperature is 10~50℃, and the reaction time is 6~24h.

6. The method for preparing modified graphene according to claim 3, wherein in the step one, product A is obtained through the following method: 90~95% of solvent A is evaporated, and the remaining substance is dried at a pressure of-0.09~-0.05 MPa.G and a temperature of 80~200℃ for 6~24h to obtain product A.

7. The method for preparing modified graphene according to claim 3, wherein in the step one, the mass ratio of diisocyanate to graphene oxide added is 2~4.2:1; the mass ratio of solvent A to graphene oxide added is 50~100:1; and the diisocyanate is diphenylmethane diisocyanate or hexamethylene diisocyanate.

8. The method for preparing modified graphene according to claim 1, wherein in the step two, the product A is dissolved in solvent A and subjected to ultrasonic treatment, then polyethylene glycol monomethyl ether is added and subjected to ultrasonic treatment, and modified graphene is obtained through reaction.

9. The method for preparing modified graphene according to claim 8, wherein the product A is first dissolved in solvent A and subjected to ultrasonic treatment for 15~60min; then polyethylene glycol monomethyl ether is added and subjected to ultrasonic treatment for 15~60min.

10. The method for preparing modified graphene according to claim 8, wherein in the step two, the reaction temperature is 10~50℃, and the reaction time is 6~24h.

11. The method for preparing modified graphene according to claim 8, wherein in the step two, modified graphene is obtained through the following method: 90~95% of solvent A is evaporated, and the remaining substance is dissolved in diethyl ether and fully stirred to obtain modified graphene.

12. The method for preparing modified graphene according to claim 8, wherein in the step two, the mass ratio of polyethylene glycol monomethyl ether to graphene oxide added is 1~5:

1. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The mass ratio of the solvent A added to the graphene oxide is 50-200:1; The molecular weight of the polyethylene glycol monomethyl ether is 200-20000 g / mol.

13. The method of claim 12, wherein the graphene is modified by adding a solvent A to the graphene oxide. The molecular weight of the polyethylene glycol monomethyl ether is 200-10000 g / mol.

14. The method of claim 3 or 8, wherein the graphene is modified by adding a solvent A to the graphene oxide. In the step one or step two, the solvent A is an organic solvent.

15. The method of claim 14, wherein the organic solvent is one of dry acetone, dry butanone, and dry tetrahydrofuran.

16. The method of claim 14, wherein the desiccant of the solvent A is one or a combination of anhydrous magnesium chloride and anhydrous magnesium sulfate.

17. The method of claim 14, wherein the drying method of the solvent A is adding 30-50% of the desiccant to the solvent A and drying at room temperature for 6-24 hours. The modified graphene is obtained by the method of any one of claims 1-17. The modified graphene of claim 18 is dispersed in a solvent B. The solvent B is one or a combination of acetone, methanol, and ethanol.

18. A modified graphene, characterized by, ​ 19. A dispersion of modified graphene, characterized in that, ​ 20. The dispersion of modified graphene according to claim 19, characterized in that, ​

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