Hydrophilicity-Controlled Asymmetric Membrane for Enhanced PM Filtration in Humid Environments

In this paper, an organic/inorganic composite PTFE/(ZnO-SiO2) nanofiber membrane (PSZM) with controllable asymmetric wettability is prepared by sequential electrospinning and cocalcination for simultaneous moisture management and PM interception. The calcination-temperature coordination of the organic layer/inorganic layer causes the hydrophilicity decrease of the inorganic layer, which is overcome by doping the ZnO in SiO2 nanofibers. Directional water transport performance can be improved by adjusting the thickness ratio of the hydrophobic/hydrophilic layer. Besides moisture management, the efficient directional water transport property of the prepared PSZM avoids the membrane fouling caused by the moisture from PM. Benefiting from the asymmetric wettability property, the prepared PSZM shows superior PM filtration efficiency (>99.99%), lower pressure drop (122 Pa), and better reusability than single-layer PTFE nanofiber membranes and SiO2 nanofiber membranes. This work provides a new functional material for organic/inorganic composite nanofiber membranes for indoor air quality control.