Superhydrophobic PAN/PBOZ/CNF aerogels for multifunctional applications: Combustion regeneration for oil/water separation, thermal insulation, and ultra-fast fire warning

Oil spills have caused serious environmental problems, making oil absorbing materials highly important. Creating polymeric aerogels with compressive resilience, superhydrophobicity, high absorption capacity, and excellent regeneration capability remains challenging. In this study, polyacrylonitrile (PAN) nanofibers prepared by electrospinning were used as the aerogel skeleton, with carbon nanofiber (CNF) serving as flame retardants and conductive agents, and benzoxazine (BOZ) as a crosslinking agent. The composite nanofiber aerogels (PAN/PBOZ/CNF-x) were prepared through freeze-drying, followed by thermal curing of ring-opening of oxazine. The low-density aerogel (0.0113g/cm 3 ) exhibited remarkable properties, including over 96% compressive recovery after 30 cycles at 60% strain, superhydrophobicity (WCA = 150.6°), and low thermal conductivity (0.0346W/m·K at 25°C). Furthermore, they demonstrated high absorption capacities between 51.4 and 104.8 g/g for various organic solvents and realized rapid separation of oil-in-water emulsion, such as dichloromethane, with a maximum separation flux of 3022.59 L m −2 h −1 . Additionally, the aerogels showed excellent thermal stability (with a char yield of 83.6 % at 800°C for PAN/PBOZ/CNF-0.1 aerogel) and outstanding flame retardancy, endowing the aerogels with combustion regeneration capability, and providing a fast (∼1s) and durable (∼400s) hazard alarm response after fire removal, retaining 81.8% of their initial absorption capacity after ten combustion-absorption cycles. The multifunctionality of PAN/PBOZ/CNF-x aerogels offers a new strategy for designing advanced multifunctional aerogels.