Super-flexible polyimide nanofiber cross-linked polyimide aerogel membranes for high efficient flexible thermal protection

Experimental preparation of lightweight and highly flexible aerogels has been a longstanding challenge, which limits their practical application in flexible thermal protection. Here, polyimide (PI) nanofiber cross-linked polyimide aerogel membranes were designed to achieve high flexibility, strong mechanical properties, and highly efficient heat-insulated performance. By taking full advantage of the perfect chemical compatibility and robust interfacial bonding strength between PI nanofibers and PI aerogel molecular chains, the PI aerogel membranes achieved the significant transformation from brittleness to high flexibility. The results demonstrate the addition of PI nanofibers exhibits significant reinforcement and toughening effect. PI nanofiber cross-linked PI aerogel membranes possess low density of 0.168 g/cm³ and low thermal conductivity of 0.0279 W/mK. Moreover, 20 wt% PI nanofiber cross-linked PI aerogel membranes exhibit high tensile strength of 2.95 MPa, while the tensile strength of pure PI aerogel is 0.27 MPa. The as-prepared PI aerogel membrane exhibited high-temperature flexible thermal protection performance, which made it a candidate for the application in modern technology, military, and aerospace.