Antibiofouling Polyacrylonitrile Ultrafiltration Membrane Functionalized by Bifunctional Terpolymer Brushes

Biofouling remains a significant challenge to the sustained performance of polyacrylonitrile ultrafiltration membranes in water treatment applications. To address this challenge, we developed a bifunctional terpolymer brush-modified PAN membrane via a novel powder-based grafting strategy. By chemically grafting a ternary polymer integrating quaternary ammonium salts for antibacterial activity, zwitterionic moieties for hydrophilicity, and condensation-reactive groups onto PAN powder prior to phase inversion, we preserved the membrane’s intrinsic pore structure and permeability. The ternary polymer for modification combines chemical condensation, antibacterial and antiadhesive properties. The zwitterionic components balance the hydrophobicity of QAS, achieving the reduction in water contact angle while maintaining 91% bacterial inhibition against E. coli in static assays. The polymer layer enhances the membrane surface’s hydration capacity and repulsion from biofouling. The Extended Derjaguin–Landau–Verwey–Overbeek theory revealed a 70% suppression of biofilm adhesion energy due to enhanced hydration repulsion. Dynamic filtration tests on simulated wastewater containing bacteria demonstrated a 53% lower flux decline rate versus unmodified PAN and 87% flux recovery postcleaning, outperforming conventional coatings. This work establishes a scalable, pore-preserving modification paradigm to engineer antibiofouling ultrafiltration membranes without compromising separation efficiency.