<p>Biofouling significantly limits the long-term performance of porous membranes in biomedical and filtration systems. In this study, active polymer coatings were fabricated on alumina membranes using ternary blends of an amphiphilic block copolymer, poly(ethylene)-<i>b</i>-poly(ethylene oxide) (PE-<i>b</i>-PEO), and a water-soluble homopolymer, poly(acrylic acid) (PAA). During film formation, the hydrophilic PEO blocks interacted with PAA, while the hydrophobic PE blocks formed the continuous matrix of the coating. After removing PAA from the blend, nanopores were generated and PEO chains were exposed on the membrane surface, resulting in a hydrophilic and nanoporous structure. The modified membranes exhibited enhanced water permeability and strong resistance to cell adhesion compared to unmodified alumina membranes. The amphiphilic composition also provided good mechanical stability and maintained wettability during continuous operation. These results indicate that the polymer-coated membranes can effectively decrease fouling while preserving structural integrity. The proposed coating strategy provides a practical route for developing durable and hydrophilic polymer membranes applicable to microfiltration and biomedical systems requiring long-term antifouling performance.</p> Graphical abstract <p>We address membrane biofouling by coating alumina with ternary blends of PE-<i>b</i>-PEO and PAA. During deposition, PEO complexes with PAA while PE forms a continuous matrix; selective PAA removal forms nanopores and exposes PEO, creating a hydrophilic porous surface. The modified membranes exhibit higher water permeability, reduced protein adsorption, stable wettability, and mechanical robustness, enabling durable antifouling in microfiltration and biomedical use.</p> <p></p>