No abstract

In this article, we reported a hierarchical structure of flower-like zinc oxide (ZnO) and poly­(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofiber (ZnO@NF) hybrid membranes for high-performance air filters. Monodispersed flower-like ZnO superstructures were fabricated using a template-free and surfactant-free hydrothermal method, and PVA-co-PE nanofiber yarns were prepared using a melt extrusion phase separation approach. The PVA-co-PE nanofiber yarns were subjected to high-speed shearing in a mixed aqueous solution of isopropanol and water to obtain a stably dispersed nanofiber suspension. The ZnO@NF hybrid air filter was obtained by coating the mixture of flower-like ZnO superstructures and the PVA-co-PE nanofiber suspension on the surface of the polypropylene (PP) meltblown nonwoven with the electret charge eliminated. The filtration efficiency of the ZnO@NF hybrid air filter increases with increasing loading amount of the flower-like ZnO superstructures, while the pressure drop decreases. The flower-like ZnO superstructures were incorporated into the nanofiber-interconnected networks, which significantly reduces the pressure drop of the pure PVA-co-PE nanofiber air filter. The filtration efficiency of the ZnO@NF hybrid air filter is much higher than that of PP meltblown nonwoven with eliminated electret charge, solving the hidden problem of electret charge dissipation during the protection process. It is demonstrated that these nanofiber hybrid air filters have great application potential in some special areas such as high-temperature and high-humidity environments.

In this work, high efficiency and multifunctional poly(vinyl alcohol‐co‐ethylene) nanofiber, Ag particle, and polypropylene (PP) meltblown nonwoven substrate composite (NF@Ag) air filters by a simple spray coating method and subsequent UV irradiation treatment are demonstrated. The water vapor transmission rate of the NF@Ag‐4 air filter is 4753.36 ± 316.75 g/(m2 d), which is higher than that of commercial PP nonwoven (4240.71 ± 354.36 g/(m2 d)). It is can be explained that the NF@Ag‐4 air filter is a Janus structure with asymmetric wettability, which enhances moisture permeability, thereby improving comfort while wearing. The NF@Ag‐2 air filter exhibits high filtration efficiency (95.80 ± 0.89%) and relatively low pressure drop (122.00 ± 1.73 Pa) without relying on the electrostatic adsorption effect. The resulting NF@Ag air filters display excellent antibacterial properties against Escherichia coli and Staphylococcus aureus, photothermal disinfection, and thermal insulation performance. Furthermore, the as‐prepared NF@Ag air filters can be simply patterned and designed as respiration monitoring sensors to precisely detect the respiratory activity and health of the human being. Therefore, it is believed that these multifunctional air filters will have good potential for applications in the removal of particular matters and breathable wearable electronic devices.