▎ 摘　　要

NOVELTY - Preparing graphene oxide modified aqueous polyurethane involves preparing pre-oxidized graphite by adding 2.5g potassium persulfate, 2.5g phosphorus pentoxide in 100mL single-necked flask that is placed in magneton, adding 12mL concentrated sulfuric acid slowly to flask, shaking flask so that above compound is dissolved in concentrated sulfuric acid. The crystalline flake graphite is added to flake in an amount of 3g, and flask is placed in an oil bath and heated to 80 degrees C and mixture is stirred at room temperature. USE - Method for preparing graphene oxide modified aqueous polyurethane (claimed). ADVANTAGE - The method enables to prepare graphene oxide modified aqueous polyurethane, which has simple operation, convenient process, and improves product quality and comprehensive performance. DETAILED DESCRIPTION - Preparing graphene oxide modified aqueous polyurethane involves preparing pre-oxidized graphite by adding 2.5g potassium persulfate, 2.5g phosphorus pentoxide in 100mL single-necked flask that is placed in magneton, adding 12mL concentrated sulfuric acid slowly to flask, shaking flask so that above compound is dissolved in concentrated sulfuric acid. The crystalline flake graphite is added to flake in an amount of 3g, and flask is placed in an oil bath and heated to 80 degrees C and mixture is stirred at room temperature. The mixture is washed in beaker containing 1L of deionized water, filtered and naturally dried to obtain pre-oxidized graphite. The oxidized graphite is prepared by adding 120mL concentrated sulfuric acid in ice water and magnetically stirred at 0 degrees C. The pre-oxidized graphite is added to stirred solution and 15g potassium permanganate is added into solution, where temperature of reaction system is maintained below 20 degrees C and stirred in ice water bath for 2 hours. The deionized water is dropped into it in an amount of 250mL to make it dilute, and temperature of process is maintained at below 35 degrees C, and placed at room temperature for 2 hours. The distilled water is added into it in an amount of 700mL to make it dilute, subjected to magnetic stirring, and hydrogen peroxide is added until solution becomes bright yellow and allowed to stand for 2 hours. The upper layer of beaker is clarified and lower layer has yellow precipitate, supernatant is poured and precipitated with 100mL hydrochloric acid aqueous solution in ratio of 1:10 to remove residual metal ions, and then allowed to stand. The upper liquid of beaker is clarified, supernatant is poured and the process is continued with distilled water until pH value of solution becomes weak acid and lower product is oxidized graphite. The oxidized graphite is purified by cutting 10cm long dialysis bag that is placed in distilled water for 30 minutes, and oxidized graphite is added into dialysis bag and its ends are tied with cotton thread. The dialysis bag is placed in large beaker containing 1L of distilled water for dialysis, where pH of water is measured at an interval of 8 hours for 5-7 days, and when oxidized graphite pH value is neutral then oxidized graphite is removed. The obtained oxidized graphite is poured into glass vessel and placed in a vacuum oven, heated to 60 degrees C with vacuum pump pumped into negative pressure for 1 day, and then placed in culture dish having 20g phosphorus pentoxide as dehydrating agent and dried for 2 days to remove residual moisture from oxidized graphite. The graphene oxide is prepared by dispersing 0.5g purified oxidized graphite in 20g water and sonicated at 60 degrees C and 100W for 1 hour to obtain graphene oxide dispersion. The sulfonic acid type aqueous polyurethane and polycaprolactone are added to a four-necked flask equipped with reflux condenser and mechanical stirrer, dehydrated at 120 degrees C at pressure of -0.01MPa for 2 hours, and cooled to 65 degrees C to obtain cooled solution. The certain amount of toluene diisocyanate is added to obtained solution and reacted for 1.5-2 hours to obtain low relative molecular weight prepolymer. The prepolymer is heated to 78 degrees, and 1-2 drops of 1,4-butanediol and dibutyltin dilaurate are added, and then acetone is added during the reaction and reacted for 2.5-3 hours to obtain reacted prepolymer. The ice water is cooled to 5 degrees C, diluted ethylenediamine sulfate as hydrophilic chain extender is added into it for chain extension for 25 minutes, and stirred at room temperature, deionized water is added and stirred at high-speed for 30 minutes and acetone is removed to obtain polyurethane emulsion. The polyurethane film is prepared by mixing and adding graphene oxide dispersion into single neck flask having aqueous polyurethane emulsion, and subjected to ultrasonic dispersion at 60 degrees C for 30 minutes, and mechanically stirred at 60 degrees C for 1 hour to obtain mixture. The mixture is poured onto glass plate and placed in a dry oven until it is dried to obtain final product.