Multi-functional nanofiber membranes with asymmetric wettability and pine-needle-like structure for enhanced moisture-wicking

Developing air cleaning membranes that simultaneously meet the needs of efficient moisture transfer, particulate matter (PM) filtration, and bacterial inhibition still faces great challenges. Herein, a membrane with asymmetric wettability and pine-needle-like nanorods (NRs) was successfully prepared through hydrothermal treatment following sequential electrospinning. The zinc oxide (ZnO) nanorods, in-situ grown on the hydrophilic polyacrylonitrile (PAN) fibers, guide water transfer by extending to hydrophobic polyvinylidene fluoride (PVDF) channels, enhancing unidirectional water transport. Meanwhile, the ZnO nanorods also release antibacterial active ingredients and increase the contact between fibers and aerosols, so harmful microbes are deactivated after the aerosols are captured by the membrane. Consequently, the PVDF/(ZnO NRs@PAN) membrane exhibits an excellent water vapor transport rate (12.47 kg m−2 d−1), PM0.3 removal efficiency (99.83%), and bacteria inhibition rate (99.99%). Moreover, the membrane maintains high filtration performance after 10-cycle filtration and cleaning. Thus, the membrane shows extensive application prospects in the scenario that involves aerosol filtration, moisture management, and microbe inhibition, such as masks, protective clothing, and fresh air systems. This work paves the way for developing multi-functional air cleaning membranes with asymmetric wettability, based on interface design and microstructure regulation.