Hydrophobic/oleophilic nanofibrous membranes for oil/water separation by suspension electrospinning and PDMS photo-induced grafting

This study presents a simple and efficient method for fabricating rubber nanofibrous membranes for oil/water separation. The process involves suspension electrospinning of styrene-butadiene rubber (SBR) latex, followed by photo-induced crosslinking to ensure insolubility and shape stability, as well as photo-induced grafting to achieve durable hydrophobicity and oleophilicity. A vinyl-terminated polydimethylsiloxane (PDMS) functionalizing agent was grafted onto the nanofibers through a thiol-ene reaction, under various functionalization conditions (e.g., solution concentrations and immersion times). FT-IR analyses confirmed successful functionalization: the resulting PDMS-grafted membranes exhibited well-defined, uniform, cylindrical fibers with an average diameter of 439 nm, a high surface area, and a structure composed of partially fused rubber nanoparticles. Contact angle measurements demonstrated stable hydrophobicity (water contact angle of 123° after 30 min, water-in-oil contact angle of 122° after 24 h) and strong oleophilicity (oil contact angle <10°). The membranes effectively separated oil from water, achieving an average separation efficiency of 99.3 % and an oil flux of 988 L m⁻² h⁻¹ after 20 filtration cycles of an oil/water mixture. These results highlight the potential of hydrophobic/oleophilic PDMS-functionalized rubber nanofibrous membranes for oily wastewater treatment and environmental remediation applications.