Temperature-triggered Ag+ release for intelligent antibacterial reverse osmosis membranes

Biofouling remains a critical challenge in polyamide thin-film composite reverse osmosis (RO) membranes, significantly impairing performance and increasing operational costs. To address this, we developed a thermoresponsive antibacterial strategy by grafting poly(N-isopropylacrylamide)-silver (PNIPAm-Ag) nanocomposites onto RO membrane surfaces via a potassium persulfate (K₂S₂O₈)-assisted grafting method. The resulting thin-film nanocomposite (TFN) membranes leverage the temperature-sensitive phase transition of PNIPAm to regulate Ag + release: at temperatures below the lower critical solution temperature (LCST), PNIPAm swells and retains Ag + ; upon temperature rise during RO operation (e.g., 37 °C), it collapses and triggers controlled Ag + release. This intelligent response enables potent antimicrobial activity, achieving inhibition rates of 99.8 % against E. coli , 98.4 % against S. aureus , and 94.6 % against C. albicans . Furthermore, the modified membranes exhibit enhanced antifouling properties with a flux recovery rate (FRR) of 91.45 %, improved long-term stability, and maintained high salt rejection (>99 %). This work presents a promising approach for developing smart, self-defensive RO membranes with on-demand antibacterial functionality.