▎ 摘　　要

NOVELTY - Crosslinked polyimide-based composite thermal insulation aerogel comprises polyimide aerogel as material framework and inorganic substance as reinforcing material, where the inorganic substance is filled in the pores of the polyimide aerogel, the polyimide aerogel has imide repeating units (1-1) and (1-2). USE - Used as crosslinked polyimide-based composite thermal insulation aerogel. DETAILED DESCRIPTION - Crosslinked polyimide-based composite thermal insulation aerogel comprises polyimide aerogel as material framework and inorganic substance as reinforcing material, where the inorganic substance is filled in the pores of the polyimide aerogel, the polyimide aerogel has imide repeating units of formula (1-1) and (1-2). Y1 = monomer segment of fluorine-containing aromatic dianhydride; X1 = divalent siloxane group of formula (2); X2 = aromatic ring-containing divalent group different from (2); R2-R7 = 1-12C monovalent hydrocarbon group; R1 and R8 = 1-12C divalent hydrocarbon group; x = 0-80; m and n = positive integers; and m/(m+n) = greater than or equal to 0.01 and less than 1. An INDEPENDENT CLAIM is also included for preparation of the crosslinked polyimide-based composite thermal insulation aerogel, comprising (i) adding stoichiometric amount of fluorine-containing dianhydride into reactor and dissolving in solvent, then adding stoichiometric amount of diaminobenzoic acid, aromatic diamine and diamino-terminated polydimethylsiloxane into the reactor according to certain molar ratio, and reacting at low temperature for 3-5 hours to obtain polyamic acid precursor solution (PAA), where the low temperature is -5 degreesC to 35 degreesC, the fluorine-containing dianhydride is 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, (4,4'-(2-(3',5'-ditrifluoromethylphenyl)-1,4-phenylenedioxy))-diphthalic anhydride, 4,4'-(2-(3'-trifluoromethylphenyl)-1,4-phenylenedioxy)-diphthalic anhydride and/or (3',5'-bis(trifluoromethyl)phenyl)pyromellitic dianhydride, the diaminobenzoic acid is 3,5-diaminobenzoic acid, 2,3-diaminobenzoic acid and/or 3,4-diaminobenzoic acid, and the aromatic diamine is o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl ether, 2,2-bis(4-aminophenyl)propane, 6,4'-diamino-2'-trifluoromethyl-2-phenylbenzimidazole, 2,5,-bis(3-aminophenyl)-1-trifluoromethylbenzene and/or 9,9-bis(4-aminophenyl)fluorene, (ii) adding chemical crosslinking agent to PAA obtained in step (i), and reacting for 0.5- 1 hour, (iii) introducing inorganic composite material into the solution obtained in (ii), ultrasonicating for 0.5-1 hour to disperse uniformly, (iv) adding dehydrating agent and imidization catalyst to the solution obtained in step (iii), and stirring for 5- 20 minutes, then pouring into mold, and allowing the gel to stand and age for 24-48 hours, (v) demolding, soaking in solvent for multiple times (12-24 hours each time) to complete solvent replacement, and drying to obtain polyimide aerogel, and (vi) heat-treating the aerogel to induce decarboxylation and crosslinking of phenyl radicals to obtain final product.