Perfluorinated superhydrophobic and oleophobic SiO2@PTFE nanofiber membrane with hierarchical nanostructures for oily fume purification

Polytetrafluoroethylene (PTFE) nanofiber membranes have been widely used in various air purification applications attributed to their excellent thermal and chemical stabilities. However, in oily fume purification, oil aerosols can easily permeate through the oleophilic membrane, which may lead to pore blocking, and increased filtration resistance and energy consumption, finally reducing the filtration efficiency and lifespan of the membrane. Herein, we report a hierarchical SiO2@PTFE nanofiber membrane by coaxial electrospinning of SiO2 nanoparticle dispersion as the shell spinning solution and PTFE emulsion as the core spinning solution, followed by in-situ surface grafting of 1H,1H,2H,2H-perfluorooctyltrimethoxysilane. The prepared amphiphobic membrane has both superhydrophobicity and oleophobicity with the water and oil contact angles of 173° and 134°, respectively. It possesses uniform pore structures, high gas permeability (697 m3 m−2 h−1 kPa−1), excellent oily fume filtration efficiency (˃99%), as well as a low pressure drop (2.5 kPa) during 60-min filtration. Furthermore, our perfluorinated amphiphobic SiO2@PTFE nanofiber membrane exhibits good reusable and stable properties. This work opens a versatile approach to design efficient functionalized membranes in the field of oily fume purification.