pH-responsive Janus membrane with anisotropic wettability for switchable oil/water emulsion separation

Janus membrane materials have demonstrated significant potential in oil–water separation applications, particularly for treating standard oil–water mixtures. However, their inability to effectively demulsify complex oil–water emulsions, especially industrial wastewater emulsions, remains a critical limitation. This study presents an innovative pH-responsive smart Janus fabric developed through Atom Transfer Radical Polymerisation (ARGET-ATRP) technology. Poly(2-(dimethylamino)ethyl methacrylate (PDMAEMA) was precisely grafted onto the surface of bilayer Janus textiles, enabling intelligent regulation of surface wettability by pH-induced chain extension/contraction transitions. Under acidic conditions (pH 4.0), the smart Janus fabric exhibited exceptional oil-in-water emulsion separation performance, achieving 99.2 ± 0.4 % separation efficiency with a maximum permeation flux of 5403.4 L/m 2 ·h·bar, while effectively intercepting oil droplets larger than 600 nm. The material maintained over 97.00 % separation efficiency after 10 operational cycles, demonstrating remarkable stability. The design of intelligent Janus fabrics with pH adjustment to achieve separation performance provides innovative ideas for industrial complex oily wastewater treatment.