Slippery hydrogel surface on PTFE hollow fiber membranes for sustainable emulsion separation

Establishing an efficient and sustainable membrane module is of great significance for practical oil/water emulsion separation. Superwetting membranes are extensively studied but unable to meet long lasting separation due to inevitable membrane fouling. Here, we construct a hydrogel inter-mediated slippery surface on polytetrafluoroethylene (PTFE) hollow fibers, and then design a flexible and swing hollow fiber membrane module inspired by fish gill respiration, which achieves sustainable emulsion separation. Vinyl silane crosslinked polyvinylpyrrolidone (PVP) hydrogel was interpenetrating with nano-fibrils of PTFE hollow fiber, thus facilitating fast water permeance while resisting oil intrusion. The liquid-like polydimethylsiloxane (PDMS) brushes were then grafted to promote oil aggregation-release from the membrane surface. Thanks to the heterogeneous surface and gill-like structure, the designed PTFE hollow fiber membrane module was able to purify emulsion in a long-term filtration process, maintaining high water permeability of 500 L m-2 h-1 bar-1 with separation efficiency over 99.9% for 5000 min. The novel technique shows its great potential to realize practical emulsions purification via solving the stubborn problem of membrane fouling and permeance decay.