Poly(acrylonitrile-co-N-vinyl-2-pyrrolidone)s (PANCNVP) were synthesized by water-phase precipitation copolymerization (WPPCP) with sodium chlorate-sodium metabisulfite as an oxidant/reducer initiator system. The copolymers were also synthesized by a solution copolymerization (SCP) initiated with azobis(isobutyroilitrile) for comparison. Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (H-1 NMR), and differential scanning calorimetry (DSC) Were used to characterize the copolymers. It was found that the copolymerization yield, the molecular weight of the copolymers, and the N-vinyl-2-pyrrolidone (NVP) conversion for WPPCP were much higher than those for SCP. Results indicated that WPPCP was a 'green' and effective method to incorporate NVP into polyacrylonitrile. The surface properties of the copolymer dense membranes were studied by water contact angle, protein adsorption, and platelet adhesion measurements. Typical results demonstrated that the introduction of NVP had little influence on the static, advancing, and receding contact angles of the dense membrane surface. However, the bovine serum albumin adsorption and the platelet adhesion were remarkably suppressed with the increase in NVP content in the copolymers. When the mole fraction of NVP in the copolymers reached 14.6 %, little platelet adhesion took place. These results revealed that the hemocompatibility of polyacrylonitrile could be greatly improved by the incorporation of NVP. (c) 2005 Elsevier Ltd. All rights reserved.