Ultra-lightweight, moisture-resistant polyimide/nano-Al2O3 composite aerogel for thermal insulation

Abstract

The escalating demand for thermal insulation has driven the exploration of polyimide (PI) aerogels. These materials have great potential in these fields due to their excellent properties of light weight, high strength and high thermal insulation efficiency. However, the lack of interaction forces between the molecular chains of pure PI aerogels results in poor mechanical properties. In most research on reinforced PI aerogels, cross - linkers are often costly and have complex preparation processes, which is not conducive to industrial applications. Meanwhile, the polar groups in the molecular chains are somewhat hydrophilic, causing water absorption and subsequent thermal performance degradation. In this study, by introducing cost - effective alumina nanoparticles into PI and functionalizing them with PDMS, we prepared PIA-PDMS composite aerogels, thereby enhancing their mechanical properties and moisture resistance. The shrinkage of the composite aerogel is 20 % lower than that of the pure PI aerogel, and the thermal conductivity is significantly reduced from 53 mW/(m·K) to 37 mW/(m·K). The contact angles of the treated aerogels are all above 130°, and the water absorption rate reduces from 205 % to 39 %, compared to the untreated aerogel. The excellent mechanical, thermal insulation and moisture resistance properties of aerogels make them favorable candidates for thermal protection materials in future aircraft and military developments.