Thermoplastic Polyurethane Nanofiber Membrane Based Air Filters for Efficient Removal of Ultrafine Particulate Matter PM_0.1

The recent pandemic of COVID-19 makes personal protective facial masks in high demand. Melt-blown or electrospun nanofibers are considered to be ideal air filter materials for resisting virus-containing fine aerosol particle, eliminating particulate matter (PM) air pollution, and protecting public health. For the commercial micro/nanofiber membranes, the general strategy for improving filtration efficiency is to simply increase the base weight. However, the influence of the base weight on overall filtration performance of air filters is usually ignored, which always leads to large pressure drop and poor breathing comfort. Here, a fabrication process using the electrospinning method with phase separation of charged droplets is reported for the thermoplastic polyurethane (TPU) nanofiber/net membranes based air filters. The average pore areas of TPU nanofiber/nets can be tunable from 0.6504 μm2 to 0.0083 μm2 via the incorporation of different Li+ ion concentrations. The optimized TPU nanofiber/net membranes based air filter demonstrates the attributes of high PM0.1 removal efficiency up to 97.08%, ∼58 Pa pressure drop, 0.061 Pa–1 quality factor, and good optical transparency with the only 6 g·m–2 base weight, which is ground-breaking compared with the existing micro/nanofiber membrane based air filters for ultrafine particle filtration.