Durable Superhydrophobic Poly(vinylidene fluoride) (PVDF)-Based Nanofibrous Membranes for Reusable Air Filters

We present a durable superhydrophobic poly(vinylidene fluoride) (PVDF)-based nanofibrous membrane to achieve high-performance air filters with reusability. We demonstrate that the additional assembly of silica nanoparticles on an electrospun PVDF nanofibrous membrane and subsequent low-surface-energy treatment enables nonwetting of various probing liquids and the membrane to exhibit a low roll-off angle (∼15°) even for 1 μL of water and artificial saliva droplets. This allows fine dust particles adsorbed on the modified PVDF membrane to be easily removed by washing and suppresses the adhesion of bacterial suspension. Moreover, the modified membrane is compatible with the ethanol sterilization procedure as the membrane exhibits no noticeable alteration in the structure and surface wettability upon spraying or dipping in 75% ethanol solution. Furthermore, by applying these modified PVDF nanofibrous membranes as a skin layer on top of an unmodified analogue, we demonstrate that air filters with high filtration performance, mechanical strength, and reusability can be prepared.