PAN/FPU Composite Nanofiber Membrane with Superhydrophobic and Superoleophobic Surface as a Filter Element for High‐Efficiency Protective Masks

Recently, because of the outbreak of COVID‐19, the demand for various types of filter elements in protective materials has increased globally. Furthermore, new requirements for the filtration performance of PM2.5 liquid (oil) particles have been put forward. In this work, Superhydrophobic and superoleophobic composite nanofibers with excellent filtration capacity for oil and salt particles are developed through the modification of polyacrylonitrile (PAN) by fluoro‐polyurethane (FPU) doping. The results show that the PAN/FPU composite nanofibers doped with 9 wt% FPU has a uniform fiber morphology with a diameter of 240 ± 30 nm. Compared to the pure PAN nanofibers, the water‐based contact angle of PAN/FPU increases from 90 ± 5° to 151 ± 5°, and the oil‐based contact angle increases from 58 ± 2° to 152 ± 3°. Importantly, at a high flow rate of 95 L min−1, the filtration efficiency of the PAN/FPU nanofiber membrane for 0.3 µm oil particles increases from 92 ± 1% to 99.2 ± 0.1%. After cyclic loading, the filtration efficiency of 0.3 µm oil particles remains above 98%. Meanwhile, the filtration efficiency for 0.3 µm salt particles remains at 98.23 ± 0.1%. The PAN/FPU nanofiber membrane developed in this work is effective in applications and has good market prospects as a protective filtration material. Polyacrylonitrile /fluoro‐polyurethane (FPU) composite nanofiber membranes have been prepared by electrospinning. The results show that nanofiber membranes have excellent superhydrophobic and superoleophobic properties when the FPU concentration is 9 wt%. In terms of filtration performance, its superoleophobic performance significantly improves the interception capacity of oily particles, and the reasons for improving the interception capacity are analyzed in detail.