▎ 摘　　要

NOVELTY - A modified graphene oxide is modified graphene oxide containing isocyanate on the surface. USE - Modified graphene oxide used in preparing graphene/silicon dioxide hybrid polyimide foam (all claimed). ADVANTAGE - The modified graphene oxide effectively reinforces graphene/silicon dioxide hybrid polyimide foam material, and the foam material has excellent toughening effect, even distribution of silicon dioxide particles on the graphene sheet, improved dispersibility, improved heat resistance, high mechanical property, and strong flame retardance. DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following: (1) production of modified graphene oxide, which involves dissolving 10 plus minus 1 g graphite powder and 3.5 plus minus 0.5 g sodium nitrate in concentrated sulfuric acid, reacting at 0-5 degrees C for 0.5-1.5 hours, adding 40 plus minus 2 g potassium permanganate, reacting at 0-10 degrees C for 1-3 hours, adjusting temperature to 32-40 degrees C, ultrasonically oscillating, reacting for 20-60 minutes, adding resulting mixture to deionized water, controlling temperature at 70-100 degrees C, mechanically stirring for 20-60 minutes, adding deionized water to stop the reaction, adding 30% hydrogen peroxide, reacting until gas is not generated, purifying with acid solution comprising water, hydrogen peroxide and sulfuric acid, dispersing in distilled water, ultrasonically oscillating for 20-60 minutes, centrifuging, extracting graphene oxide aqueous solution, preparing anhydrous graphene sheet, grinding into powder, mixing 200 plus minus 10 mg graphene oxide and dimethylformamide, ultrasonically processing for 20-60 minutes, adding 5-6.5 g diisocyanate, ultrasonically treating for 20-60 minutes, adding 2-3 drops of catalyst dibutyltin dilaurate, heat preserving at 50 plus minus 5 degrees C for 48-60 hours, washing with acetone, centrifuging, and drying; (2) graphene/silicon dioxide hybrid polyimide foam, which comprises 30-35 pts. wt. benzophenone tetracarboxylic dianhydride, 19-21 pts. wt. diaminodiphenyl ether, 5-40 pts. wt. methanol, 0.01-0.1 pt. wt. 3-aminopropyltriethoxysilane, 6-20 pts. wt. ethyl orthosilicate, and 10-20 pts. wt. modified graphene oxide; and (3) preparation of graphene/silicon dioxide hybrid polyimide foam material, which involves adding benzophenone tetracarboxylic dianhydride to methanol, heating at reflux at 70 plus minus 5 degrees C for 1.5-2.5 hours, adding diaminodiphenyl ether, heating at 70 plus minus 5 degrees C for 1.5-2.5 hours, adding 3-aminopropyltriethoxysilane, heating for 1-1.5 hours, adding modified graphene, reacting for 1-1.5 hours, adding ethyl orthosilicate, reacting for 20-60 minutes to obtain precursor solution of graphene/silicon dioxide hybrid polyimide foam, heating precursor solution, removing excess solvent, polishing dried precursor, sieving using pulverizer to obtain precursor powder of uniform particle size, adding precursor powder to homemade mold, foaming, and imidizing in microwave oven.