A Review of Silica/Polyimide Composite Aerogels: Synthesis, Properties, and Applications

Polyimide aerogels (PIAs) are a class of high-performance organic aerogel materials distinguished by their excellent thermal stability, low density, and highly porous structures. Due to their superior thermal insulation performance, low dielectric constant, and excellent mechanical properties, PIAs have attracted significant attention for applications in aerospace, electronic packaging, and thermal protection. However, their susceptibility to severe dimensional shrinkage and structural collapse at elevated temperatures has considerably hindered their practical engineering applications. To overcome these limitations, researchers have incorporated silica aerogels (SAs) as thermally stable inorganic reinforcing phases to fabricate silica/polyimide (SA/PI) composite aerogels. By regulating the type of SAs, doping strategies, and preparation methods, significant improvements have been achieved in the thermal stability, flame retardancy, hydrophobicity, and high-temperature shrinkage resistance of these composite materials. This review systematically summarizes recent progress in the synthesis methods, thermal safety performance, and representative applications of SA/PI composite aerogels, with particular emphasis on future development directions. It aims to offer theoretical insights and technical references for the optimized design and scalable engineering application of these advanced multifunctional PIAs.