Mussel-inspired approach to cross-linked functional 3D nanofibrous aerogels for energy-efficient filtration of ultrafine airborne particles

Abstract Polymer aerogels fabricated using conventional methods typically have relatively narrow mono-modal pore size distribution (PSD), and relatively thick and tight pore walls. Herein, inspired by mussel glue, cross-linked three-dimensional (3D) polyacrylonitrile (PAN) nanofibrous aerogels (NFAs) with ultrahigh porosity, hierarchical porous structures, and good compression resistance are successfully fabricated via electrospinning, facile polydopamine (PDA) coating and crosslinking by ferric ions (Fe 3+ ) followed by freeze-drying. Morphology characterization and compression tests show that both multiple hydrogen bonding facilitated by the PDA coating and Fe 3+ -PDA coordination bonding could effectively induce the formation of inter-fiber junctions, enhancing compression resistance of the 3D NFAs and leading to hierarchical porous structures with a very wide PSD. When a thin layer of the optimized 3D NFA with a large specific surface area (85.7 m 2  g −1 ) is combined with a commercial air filter, the composite filter obtained exhibits high filtration efficiencies of 99.72% and 99.85% for airborne particles with sizes of 3+ , and high porosity and hierarchical porous structures of the 3D NFAs.