Multilevel structured polyacrylonitrile/silica nanofibrous membranes for high-performance air filtration

• Innovative fabrication of PAN/SiO2 NPs filter media with multilevel structure.
• Correlation between surface roughness and filtration performance was verified.
• Non-circular singe fiber filtration mechanism of PAN/SiO2 NPs membranes was proposed.
• Multilayer filter media showed high-performance fine particulate air filtration.

As engineers strive to develop high-performance filtration membranes with structural alternatives, the challenges and costs of processing often limit creative innovation. Here, we describe a powerful yet economic strategy for fabricating multilevel structured nanofibrous membranes within a single filter medium, which is constructed by the accumulation of bimodal sized and silica nanoparticles (SiO2 NPs) incorporated electrospun polyacrylonitrile (PAN) nanofibrous membranes. By simply varying the composition of precursor solutions and layer-by-layer assisted stacking structure, individual fibers within the medium can conformally be endowed with non-circular cross section, or rough surface to form a skeletal frame-worked membrane with complimentary filtration efficiency (99.989%) and pressure drop (117 Pa) for 300–500 nm NaCl aerosol particles. The results suggested that this cost-effective filter media could be used as promising materials for a variety of potential applications in respiratory protection equipment, high efficiency particulate air filters, and ultra-low penetration air filters.