Bilayered Nanofibrous Membrane With Wettability Gradient for Efficient PM0.3 Filtration and Dynamic Moisture Management

ABSTRACT Addressing air quality challenges under climate change requires filtration materials that maintain reliable performance in high‐humidity environments. Traditional filters often exhibit reduced efficiency and increased breathing resistance due to moisture accumulation. In this study, a bilayered nanofibrous membrane integrating poly(vinylidene fluoride‐co‐trifluoroethylene) (PVDF‐TrFE) and polyacrylonitrile (PAN) was fabricated, featuring a heterogeneous interface for efficient moisture management and high filtration performance. A wettability gradient was established by adjusting the spinning time ratio between the hydrophobic PVDF‐TrFE and hydrophilic PAN layers, promoting water vapor transport via differential capillary action. This gradient synergistically enhances both moisture management and particulate matter (PM) filtration. The PVDF‐TrFE layer, rich in electronegative fluorine atoms, exhibits strong electrostatic adsorption with a surface potential of 7.36 kV. It achieves a PM 0.3 filtration efficiency of 97.37%, significantly higher than single‐layer counterparts, and a high quality factor of 0.0203 Pa −1 . The cyano functional groups present in the PAN layer form hydrogen bonds with water molecules, resulting in an equilibrium moisture absorption of 31.4% and a water vapor transport rate of 5.51 kg m −2 h −1 . These findings demonstrate a practical strategy using wettability gradients to develop next‐generation filtration materials for humid and heat‐sensitive environments, including medical isolation and specialized industrial applications.