Stable manufacturing of electrospun PVDF/FPU multiscale nanofiber membranes and application of high efficiency protective mask filter elements

Effective particulate matter (PM) filtration in air has become a significant focus of scientific research due to the increased focus on environmental health and sustainable development. In this work, efficient nanofiber scale preparation technology is realized, based on our self-developed electrospinning equipment. Polyvinylidene fluoride/fluorinated polyurethane (PVDF/FPU) nanofiber composite membrane with multi-scale structure was designed and prepared, and successfully applied in the field of air filtration. PVDF/FPU ultrafine nanofibers with a diameter of 30 ± 5 nm were produced by employing high-conductivity dilute solution electrospinning. Subsequently, a PVDF/FPU composite nanofiber membrane material with a double-layer multiscale structure was constructed by adjusting the proportion and sequence of the spinning units of different scales. The results indicate that this double-layer, multiscale PVDF/FPU composite nanofiber membrane features a minute average pore size (0.36 μm), a high porosity rate (94.56 %), and outstanding hydrophobic properties (with a contact angle of 138.6°). This demonstrated exceptional filtration efficiency (99.98 %) and low filtration resistance (67 Pa) under test conditions of 32 L/min. After 10 wash cycles, the filtration efficiency remained above 99 %, indicating remarkable stability. Furthermore, the COMSOL simulation software was utilized to analyze the gradient filtration mechanism of the nanofiber membrane, which correlated well with the experimental results. The double-layer multiscale PVDF/FPU nanofiber composite membranes developed during this study offers a novel approach for creating highly efficient, low-resistance air-filtration materials.