“In Situ Reaction Cross-Linking” Strategy for Large-scale Construction of Highly Hydrophobic and Superelastic Polyimide Nanofiber Aerogels for Efficient Oil–Water Separation

Polyimide nanofiber (PINF) aerogels, characterized by low density, high-temperature resistance, and excellent thermal insulation, are a promising class of organic porous materials. However, the scalable and controlled fabrication of PINF aerogels remains a significant challenge for practical applications. In this study, we developed an ″in situ reaction cross-linking″ strategy to fabricate highly hydrophobic and superelastic PINF aerogels with efficient oil–water separation capabilities. Using electrospun poly(amic acid) nanofibers based on BPDA and ODA as the precursor, a robust, self-cross-linked nanofibrous network was formed through interfacial contact reactions during the in situ thermal imidization process. This method enabled the successful preparation of Large-area PINF aerogels (460 mm × 340 mm). The resulting aerogels exhibit superelasticity, achieving complete recovery after 80% compression at an ultralow density of 11.92 mg cm –3 and maintaining structural integrity over 1000 compression cycles under 50% compressive strain. They also show high hydrophobicity with a water contact angle exceeding 135°. For dichloromethane, the aerogels achieve a high flux of up to 127,388.5 L m –2 h –1, adsorption capacity up to 74 g g –1, and separation efficiency greater than 99.99%. This work provides a highly processable foundation for manufacturing functional PINF aerogels and facilitates their large-scale production and application.