▎ 摘　　要

NOVELTY - Preparing composite material comprises ultrasonic dispersing graphene oxide powder in organic solvent, adding siloxane modifying agent in the dispersion liquid to react, washing and drying to obtain silicon (Si)-modified graphene powder, adding Si-modified graphene, dianhydride and diamine mixture in non-proton polar solvent, performing insitu polymerization to obtain the Si-modified graphene/polyamide precursor acid solution, mixing polyimide and silicon-modified graphene, heating at 30-100 degrees C to remove the solvent, raising the temperature, and keeping the temperature for 1-4 hours. USE - The method is useful for preparing composite material (claimed). DETAILED DESCRIPTION - Preparing composite material comprises taking graphite oxide from natural crystalline flake graphite having size of 8000-50 meshes as raw material, performing improved Hummer method to graphite oxide powder, ultrasonic dispersing graphene oxide powder in organic solvent for 0.5-2 hours to obtain 0.5-5 mg/ml graphene dispersion liquid, adding siloxane modifying agent in the dispersion liquid, reacting at 30-180 degrees C for 1-24 hours, washing, drying to obtain silicon (Si)-modified graphene powder having Si mass content of 2-13%, thickness of 0.8-1.4 nm and grain diameter of 2-60 mu m, adding Si-modified graphene, dianhydride and diamine mixture in non-proton polar solvent, performing insitu polymerization at -10 degrees C to -30 degrees C for 1-36 hours under the protection of nitrogen to obtain the Si-modified graphene/polyamide precursor acid solution with solid content of 5-40 wt.%, mixing 80-99.99% polyimide and 20-0.01% of silicon-modified graphene, heating at 30-100 degrees C to remove the solvent, raising the temperature to 100-450 degrees C, and keeping the temperature for 1-4 hours. The non-protonic organic solvent is N,N-dimethyl formamide, N,N-dimethyl acetamide dimethyl or sulfoxide or N-methyl pyrrolidone. The siloxane modifying agent is 3-amino propyl triethoxy silane or 4-amino phenyl triethoxy silane according to mass ratio of 1:3:3-18. The dianhydride is 4,4'-diphthalic anhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, 4,4'-oxybis phthalic anhydride, 3,4'-oxydiphthalic anhydride, 3,3',4,4'-diphenyl sulfone dianhydride, 4,4'-(hexafluoro isopropylidene)-2-phthalic anhydride, pyromellitic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride, bicyclo (2.2.2) oct-7-ene-2,3,5,6- tetracarboxylic acid dianhydride, 3,3',4,4'-diphenyl sulfone dianhydride, 4,4'-(hexafluoro isopropylidene) diphthalic anhydride, naphthalene-1,4,5,8-tetracarboxylic acid dianhydride, 3,4'-oxydiphthalic anhydride or 3,4,9,10-perylene dianhydride. The diamine is 4,4'-diaminodiphenyl ketone, 1,4-phenylenediamine, 4,4'-diaminodiphenyl methane, 4,4'- diaminodiphenyl ether, 2,2-bis (4-(4-aminophenoxy)phenyl) propane, bis(4-aminophenyl) sulfone, 1,4-bis (4'' aminophenoxy) benzene, 2,2'-bis(difluoromethyl) benzidine, 4,4'-diamino-3,3'-biphenyldiol, 4,4'-diamino-octafluorobiphenyl, 3,3'-dihydroxybiphenyl, 3,3'-diaminodiphenyl methane, 3,4'-diaminodiphenyl methane, 4,4'-diamino-3,3'-diphenyl dimethyl methane, 4,4'-methylenebis(2-chloroaniline), 4,4'- methylene-bis(2-ethyl-6-methyl aniline), 3,3'-diaminodiphenyl, 1,3-bis (3-aminophenoxy)benzene, 1,3-bis (4-aminophenoxy) benzene, 3,4'-diaminodiphenyl ether, bis(4-aminophenyl)sulfide, bis (3-aminophenyl) sulfone, bis(4-(3-aminophenoxy) phenyl) sulfone, bis(4-(4-amino phenoxy) phenyl) sulfone, 2,2-bis(3-amino-4-methylphenyl) hexafluoropropane, 2,2-bis(4-(4-aminophenoxy) phenyl) hexafluoropropane, 2,2 -bis(3-amino-4-light phenyl) hexafluoropropane or 2,2-bis(3-aminophenyl) hexafluoropropane.