Molecular Engineering Design for Ultra-Strong Polyimide Aerogels: From Synthesis to Performance

Polyimide (PI) aerogel has been widely applied in aerospace and thermal management owing to its excellent thermal resistance, high strength, and low thermal conductivity. Compared with supercritical CO 2 drying or freeze-drying for fabricating PI aerogel, the ambient pressure drying (APD) strategy presents huge potential due to its advantages, such as simple drying equipment, large-scale production, and relatively low cost. However, the bottleneck for fabricating PI aerogel via APD mainly lies in the collapse of the gel structure. Herein, we proposed an APD strategy to fabricate superstrong PI aerogels through the adoption of highly rigid 3,3“,4,4”-biphenyl tetracarboxylic dianhydride (BPDA) and 2,2’-dimethyl-4,4’-diaminobenzene (DMBZ), in which the steric hindrance of methyl groups can inhibit the close packing of polymer chains. Cross-linking by 1,3,5-tris(4-aminophenoxy)benzene (TAB) further enhances the molecular rigidity and network stability. The as-obtained PI aerogel exhibits high porosity (∼91.4%), excellent mechanical strength (compressive modulus, ∼54.4 MPa), and fire resistance with a low peak heat release rate (PHRR, ∼26.5 W g –1 ), presenting huge potential in industrialization and wide engineering applications.