Structure and properties of polyimide aerogels with different skeleton flexibilities

ABSTRACT In order to better understand the influences of polyimide (PI) skeleton structure and freeze-drying process on the properties of PI aerogel materials, PI molecular chains (ODPA-ODA, BPDA-ODA, BPDA-PPDA) with different stiffnesses and flexibilities were designed and a series of PI aerogels were accordingly fabricated by freeze-drying technique. The aerogels produced featured light weight (density of 0.01–0.16 g/cm3) and high flexibility, and their density, pore structure, and compress recovery performance could be well controlled by delicately tuning the molecular chain structure and solid contents of the poly (amic acid) salt solution. In addition, a hard PI aerogel with enhanced compressive strength was obtained by quick-freezing in liquid nitrogen.