While polyethersulfone (PES) represents outstanding oxidative, thermal and hydrolytic stability as well as good mechanical and film-forming properties, the hemocompatibility of PES membrane must be dramatically enhanced to reduce injections of anticoagulants during hemoclialysis. In this study, a comblike amphiphilic block copolymer poly (vinyl pyrrolidone)-block-poly (acrylate-gralt-poly (methyl methacrylate))-block-poly-(vinyl pyrrolidone) (PVP-b-P(AE-g-PMMA)-b-PVP) was synthesized via reversible addition-fragmentation chain transfer polymerization and used to modify PES membrane via a liquid-liquid phase separation technique. The surface structure of the modified membrane were characterized by using X-ray photoelectron spectroscopic analysis, Fourier transform infrared and water contact angle measurement The modified PES membrane showed low hemolysis ratio, improved hydrophilicity, suppressed platelet adhesion and prolonged activated partial thromboplastin time. And the modified membranes showed high PBS solution (or water) flux and good protein anti -fouling properties. The dramatic performance enhancement is attributed to its unique surMce architecture, which may be formed by migration and sell assembly of PVP-b-P(AE-g-PMMA)-b-PVP during phase separation. In the surface layer of the modified membrane, PVP chain formed functional brush while PMMA chain embedded in the membrane substrate. The highly branched chains of P(AE-g-PMMA) block endowed the modified membrane with good stability, which has potential to be used in blood purification. (C) 2014 Elsevier B.V. All rights reserved,