High‐Temperature Resistant Polyimide Aerogels With Extreme Condition Tolerance Constructed by In Situ Skeleton Encapsulation Growth

Abstract Polyimide aerogel (PIA) can enable to withstand the extreme conditions in a great measure due to their exceptional thermal stability and excellent mechanical toughness properties derived from the rigid‐ring structures, which are rather promising alternatives in terms of high‐performance thermal protection materials for aerospace field. However, PIA usually suffers from poor dimensional stability at high‐temperature atmosphere, accordingly leading into the degradation of macroscopic features, eventually restricting their extreme‐ambient applications. Here, an in situ skeleton encapsulation growth strategy is proposed to modulate aerogel networking skeleton construction pattern, namely forming the binary organic–inorganic nature skeletons originated from PIA nanoscale structures encapsulated with polymethylsilsesquioxane. The resulting aerogel demonstrates superior dimensional stability (linear shrinkage down to 1.11% even experiencing at 300 °C for 3000 s) despite facing high‐temperature heat flux shock, suggesting an excellent high‐temperature resistant ability depending upon encapsulated Si‐O‐phase‐layer networking skeletons formation and intrinsic strong chemical bonds of polyimide chains. Further, the aerogels own the exceptional extreme‐condition tolerance when subjected to thermal shock cycling (−196 °C—300 °C), and fantastic flame retardancy at 1200 °C. This approach to developing PIA broadens the applicability of high‐performance PIA and holds significant potential for aerospace thermal protection, particularly in extreme conditions.