Abstract To combat biofouling-induced flux decline in membrane processes, we engineered low-cost, environmentally friendly polyester copolymers functionalized with cationic benzyldimethyl[2-[(2-methyl-1-oxoallyl)oxy]ethyl]ammonium chloride (DMBC) and poly(ethylene glycol) methacrylate (PEGMA) via phase inversion. The cationic DMBC induced electrostatic repulsion, yielding ultrafiltration (UF) membranes with tunable pore structures and robust antifouling performance (85.4 % flux recovery after pr