Design of inherently polarized nanofiber-based membranes for superior filtration performance

As airborne particulate matter (PM) such as pathogens and ultrafine dust threaten the human health, air quality control technologies are becoming increasingly important. Herein, poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP) nanofibers with various fiber diameters and pore size distributions were prepared using various compositions of volatile (acetone) and less volatile N,N-dimethylformamide (DMF) solvent mixtures to design the optimum filtration media. Morphologies and molecular configurations were examined thoroughly with respect to the filtration performance. Among the various solvent compositions, the specimen prepared with the lowest DMF content (denoted as ePVdF-HFP55) showed the best filtration performance, with a filtration efficiency of 99.95% and a pressure drop of 29.0 mmH₂O. The quality factor (QF) of ePVdF-HFP55 (0.0266 Pa⁻¹) is superior to that achieved in electrospun nanofibrous media in previous works. In addition, the QF was further improved to 0.0276 Pa⁻¹, with a remarkably reduced resistance of 14.45 mmH₂O achieved by employing the layered nanofiber media with a PVdF-HFP top layer. Our work demonstrates that optimization of the inherently polarized nanofiber synthesis is a fruitful pathway to enhancing the filtration performance of air filter media.