Making Accessible and Attractive Porosities in Block Copolymer Nanofibers for Highly Permeable and Durable Air Filtration

Submicron particulate matter (PM) can penetrate deeply into human tissue, posing a serious threat to human health. However, the electrostatic charge of commercial respirators is easily dissipated, making it difficult to maintain long-term filtration. Herein, a hierarchically porous filter based on nanofibers with accessible porosity and particulate-attractive surfaces, achieving significant filtration performance is developed through polarity-driven interactions. This is achieved by selective swelling of electrospun nanofibers of the block copolymer of polysulfone and poly(ethylene glycol) (PSF-b-PEG), in which the originally solid nanofibers are 3D perforated with the PEG chains lined along the pore walls. Thus-produces nanofiber filters exhibit a long-term continuous filtration with an efficiency of over 95% for PM_0.3 and a low pressure drop of only 40 Pa. In particular, it maintains superior filtration performance even under high particle concentrations and high humidity conditions. Additionally, the filter exhibits high air permeability (10814 m³ m^-2 h^-1 kPa^-1) and water vapor transmission rate (3707 g m^-2 d^-1). This work provides new strategies and understandings on the development of porous structures simultaneously exhibiting high gas permeability and efficient particulate rejection.