Electrospinnability and Air Filtration Efficiency of PVDF Nanofibers: The Role of Electrospinning Solution Properties

Abstract

This study successfully refined the electrospinnability window for polyvinylidene fluoride (PVDF) nanofiber membranes by systematically investigating solvent systems to achieve bead-free morphologies mapped within a Teas ternary diagram. The correlation between fiber morphology and solution properties, such as viscosity, surface tension, and conductivity, allowed for a reproducible approach to fabricate high-performance nanofiber membranes. Using DMSO:Ac/60:40 solvent ratio and a 14% w/w PVDF concentration, following a 3² factorial DoE, bead-free fibers with an average diameter of ~700 nm were produced. This solvent selection and morphology refinement enhanced the crystalline β phase, which promoted intern-oriented dipoles that were enhanced by an additional charge induction effect. This led to increased volume and surface charges on the membrane, enhancing electrostatic filtration mechanisms. Filtration tests at a 5.3 cm/s face velocity showed that a 10.4 g/m² bead-free PVDF fiber membrane enriched with a β phase and additional induced surface charge, outperformed bead-on-string structures and a commercial high efficiency particulate air (HEPA) filter, achieving HEPA-grade efficiencies $\left({\eta }_{\text{MPPS}}=0.995\text{and}{\eta }_{\mathrm{PM}0.3}=0.998\right)$ with low air resistance $\left(\mathrm{\Delta P}=112.7\mathrm{Pa}\right)$. These results highlighted the role of morphology and charge characteristics in filtration efficiency and provided a method for PVDF electrospinning to meet the growing demand for effective ultrafine PM filtration.