Tough and lightweight polyimide/cellulose nanofiber aerogels with hierarchical porous structures as an efficient air purifier

With the increasing severity of health problems caused by air pollution, the demand for high-quality air filtration aerogel materials is increasing. Aerogels with a hierarchical porous structure are beneficial for filtering dangerous small-sized particles, especially for the removal of nanoparticles in the air. In this study, composite nanofibrous aerogels with clear hierarchical porous structures were successfully prepared by the introduction of cellulose nanofibers (CNF) into a polyimide nanofiber (PINF) system by self-assembly and freeze-drying technology. Notably, solvent-induced crystallization was used to improve the pore structures of the nanofiber aerogels. The resulting aerogel samples exhibited an extremely low density and a hierarchical porous structure. More importantly, the samples exhibited high filtration efficiency (99.69% for PM0.3) and a low pressure drop (230 Pa) at a lower base weight, rendering them promising air filtration materials for the applications in more complex environments.