Stabilized electret polyimide nanofiber membrane with superoleophilic properties for oily aerosol filtration

Complex-component oily aerosols are more harmful to health than solid particulates, but current filtering materials are ineffective against high-temperature liquid-phase contaminants, highlighting the need for better purification methods. Herein, polyimide (PI) electrospun nanofiber membranes with spindle-bead structures and electret treatment are developed. The electret in nanofiber membranes captures oily aerosols, while spindle-bead structures create a Laplace pressure gradient that directs oil droplets from fibers to spindle nodes, enabling droplet detachment. The nanofiber filter membranes show stable surface potential (2.05 kV), and superior lipophilicity (dioctyl sebacate [DEHS] wetting time of 6 s), which enable the membranes to achieve efficient filtration of oily aerosols (>99.8%) and low-pressure resistance (∼68 Pa). Moreover, the membranes demonstrate exceptional thermal stability, retaining structural integrity and mechanical properties at 200 °C, making them ideal for high-temperature oily aerosol filtration. This strategy opens up a pathway for the design of high-temperature oily aerosol filtration materials.