Bioinspired Design of PVDF/SiO₂-<i>g</i>-PEGDA Membranes Via Vapor-Induced Phase Separation for Oil/Water Separation

The eco-friendly nature and energy efficiency of polymeric membranes have established them as pivotal materials for oil-in-water emulsion separation. However, persistent membrane fouling caused by oil deposition remains a major challenge, significantly hindering their practical implementation in industrial settings. In this work, thiol-ene photochemistry was employed to synthesize PEGylated silica nanoparticles (SiO₂-<i>g</i>-PEGDA) using poly(ethylene glycol) diacrylate (PEGDA) and hexanedithiol (HD) as monomers. Biomimetic PVDF membranes were engineered via vapor-induced phase separation (VIPS) by integrating SiO₂-<i>g</i>-PEGDA nanoparticles, followed by secondary coagulation in a dopamine (DA) solution. The experimental results demonstrate that the biomimetic membranes exhibit a characteristic sponge-like cross-sectional morphology and well-defined rough surface microstructures, which are attributed to the synergistic roles of SiO₂-<i>g</i>-PEGDA as nanofillers and DA as interfacial cross-linker during secondary phase separation. Energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses confirm that the combined action of nanoparticles and PDA significantly increases the density of hydrophilic functional groups on membrane surfaces and within pore channels. The membranes exhibit excellent hydrophilicity and underwater superoleophobicity, achieving an outstanding emulsion flux of 3537 Lm^-2 h^-1 bar^-1 and an oil removal efficiency of 98.5%. After 15 cycles of oil-water separation, the membranes maintain a high flux recovery rate of 85.6%. Moreover, the biomimetic membranes possess exceptional operational stability, as evidenced by consistent surface wettability under organic solvents, strong acid and high-salinity conditions.