▎ 摘　　要

NOVELTY - Preparing phenyl silsesquioxane/graphene oxide/polyimide three-phase composite film comprises e.g. (i) dissolving expanded graphite with mixed acid solution, mechanically stirring, then adding potassium permanganate, transferring to water bath boiler, adding deionized water, adding hydrogen peroxide solution, centrifuging obtained liquid, drying and grinding resulting product to obtain graphite oxide powder, then adding prepared graphite oxide powder into deionized water, ultrasonically vibrating to obtain graphene oxide, then mixing concentrated nitric acid and concentrated sulfuric acid to obtain mixed acid solution, (ii) adding N,N'-dimethylacetamide solution into graphene oxide obtained in step (i), ultrasonically dispersing to obtain dispersion, then adding 4,4'-diaminodiphenyl ether I into dispersion, then adding silane coupling agent, adding 4,4'-diaminodiphenyl ether II and pyromellitic dianhydride to obtain nano phenyl silsesquioxane/graphene oxide/polyamic acid solution. USE - The method is useful for preparing phenyl silsesquioxane/graphene oxide/polyimide three-phase composite film. ADVANTAGE - The method improves the thermal performance and mechanical performance. DETAILED DESCRIPTION - Preparing phenyl silsesquioxane/graphene oxide/polyimide three-phase composite film comprises (i) dissolving expanded graphite with mixed acid solution under ice water bath conditions, mechanically stirring until expanded graphite is dissolved, then adding potassium permanganate, mechanical stirring until potassium permanganate is completely dissolved for 1-2 hours, transferring to water bath boiler at 35 degrees C for 1-2 hours, then raising temperature of water bath boiler to 35-98 degrees C, adding deionized water using separatory funnel, heating at 98 degrees C for 1-2 hours, then adding 30% strength hydrogen peroxide solution until the solution turns bright yellow, then diluting bright yellow solution, filtering reaction product, repeatedly centrifuging obtained liquid to pH of 7, drying and grinding resulting product to obtain graphite oxide powder, then adding prepared graphite oxide powder into deionized water, ultrasonically vibrating for 3 hours, and drying to obtain graphene oxide, then mixing concentrated nitric acid and concentrated sulfuric acid in a volume ratio of 1:3 to obtain mixed acid solution, where volume ratio between mass of expanded graphite and mixed acid solution is 1 g:80-120 ml; mass ratio between expanded graphite and potassium permanganate is 1:5-7; and volume ratio between expanded graphite and deionized water during heating process is 1 g:180-220 ml, (ii) adding N,N'-dimethylacetamide solution into graphene oxide obtained in step (i), and ultrasonically dispersing to obtain dispersion, then transferring dispersion to constant temperature water bath boiler, adding 4,4'-diaminodiphenyl ether I into dispersion, stirring and reacting at 60 degrees C for 20-28 hours under nitrogen atmosphere, then adding phenyl silsesquioxane, ultrasonically dispersing, then adding silane coupling agent, stirring until to mix, then adding 4,4'-diaminodiphenyl ether II and pyromellitic dianhydride, and stirring at room temperature for 12 hours to obtain nano phenyl silsesquioxane/graphene oxide/polyamic acid solution, where mass ratio between graphene oxide and 4,4'-diaminodiphenyl ether I is 2:3; addition amount of graphene oxide is 0.1-0.9% of the total mass of 4,4'-diaminodiphenyl ether II and pyromellitic dianhydride; addition amount of phenylsilsesquioxane added is 1-3% of the total mass of 4,4'-diaminodiphenyl ether II and pyromellitic dianhydride; volume ratio between mass of 4,4'-diaminodiphenyl ether II and N,N'-dimethylacetamide solution is 1 g:12 ml; and molar ratio between 4,4'-diaminodiphenyl ether II and pyromellitic dianhydride is 99:100, and (iii) transferring nano phenyl silsesquioxane/graphene oxide/polyamic acid solution obtained in step (ii) to constant temperature water bath boiler at 50 degrees C for 30 minutes by heat degradation, paving, heating at 300 degrees C using gradient for thermal imidization, and cooling to room temperature to obtain POSS/ODA-GO/PI composite film.