Preparation and thermal insulation properties of lightweight high-strength polyimide aerogels containing benzoazole structures

Polyimide (PI) aerogels, serving as thermal insulation materials in extreme environments, stand out for their exceptional high temperature stability and superb thermal insulation properties, rendering them ideal for aerospace, transportation, and specialized equipment industries. However, conventionally synthesized PI aerogels suffer from significant drawbacks in mechanical properties and thermal stability, limiting their practical applications. To overcome this challenge, we successfully synthesized polyimide aerogels using biphenyl-3,3,4,4 ' tetracarboxylic dianhydride (BPDA), 5-amino-2-(4-aminophenyl)benzimidazole (PABZ), and 5-amino-2-(4-aminophenyl)benzoxazole (APBO) followed by supercritical carbon dioxide drying. These synthesized PIs exhibit remarkable thermal stability, with high thermal weight loss temperatures (T-d5 %=595-611 degrees C) and high glass transition temperatures. Additionally, these novel PI aerogels demonstrate exceptional thermal insulation properties, high specific surface area, and extremely small pore size. Furthermore, boasting a low dielectric constant (epsilon=1.72), these newly developed PI aerogels offer along with excellent mechanical properties, holding substantial promise for applications in the forthcoming generation of advanced aerospace and specialized equipment materials.