Star polymer-mediated in-situ synthesis of silver-incorporated reverse osmosis membranes with excellent and durable biofouling resistance

Biofouling mitigation for water purification membranes is critically important for the efficient separation process. Most anti-biofouling thin-film nanocomposite (TFN) membranes have been incorporated with biocidal nanomaterials via ex-situ hybridization, often leading to performance deterioration and ineffective nanomaterial incorporation. Here, we present a new in-situ hybridization strategy for the fabrication of silver-incorporated TFN (CD-Ag-TFN) reverse osmosis (RO) membranes exhibiting excellent anti-biofouling and separation performance by utilizing an amine-functionalized star polymer. CD-Ag-TFN membranes were formed by adding a Ag precursor (AgNO₃) to an aqueous solution containing poly(acryloyl hydrazide)-branched star polymers (CD-PAHs) prior to interfacial polymerization with trimesoyl chloride (TMC). Numerous amine groups in CD-PAH strongly adsorbed Ag⁺ ions via complexation, which were subsequently converted to Ag or AgCl nanoparticles, while simultaneously forming a polyamide (PA) selective layer via the reaction with TMC, consequently creating a uniform PA-Ag hybrid network. Due to its greater hydrophilicity and high crosslinking density, the optimized CD-Ag-TFN membrane exhibited RO performance, which is better than that of the CD-PAH-assembled control (CD-TFC) and comparable to than that of recently reported other lab-made RO membranes. Importantly, the robust and effective incorporation of Ag endowed the CD-Ag-TFN membrane with remarkably long-lasting anti-bacterial activity and greater anti-biofouling performance than control CD-TFC.