This study reports a novel and systematic strategy on the preparation and characterization of pH-responsive and anti-fouling composite membranes via one-pot in-situ cross-linked copolymerization. Typical commercial polyethersulfone (PES) is used as membrane matrix; poly (methyl methacrylate-co-acrylic acid) (P(MMA-AA)) and poly(methyl methylacrylate-co-4vinyl pyridine) (P(MMA-4VPy)) are applied as model pH-responsive copolymers. The casting solutions are directly synthesized by one-pot in-situ cross-linked copolymerization of MMA, AA/4VPy and cross-linker in PES solutions; then, composite membranes are obtained by a liquid-liquid phase inversion method. ATR-FTIR, water contact angle, membrane morphology, pH sensitivity and reversibility, protein anti-fouling property, and Cu2+ adsorption capacity for the composite membranes are systematically investigated. The cross-section SEM data indicated that the composite membranes owned typical finger-like structure; while the surface SEM images indicated that the in-situ copolymerized system exhibited excellent miscibility between PES and copolymers. The pH-responsive tests proved that the PES/P(MMA-AA) and PES/P(MMA-4VPy) membranes owned remarkable and reversible pH-responsive performance. Protein ultrafiltration experiments showed that the composite membranes exhibited excellent anti-fouling property. Furthermore, the prepared composite membranes exhibited good Cu2+ adsorption capacity. The results demonstrated that the proposed in-situ cross-linked copolymerization provided a facile and practical approach to fabricate pH-responsive and antifouling membranes for various applications. (C) 2014 Elsevier B.V. All rights reserved.