Two sulfobetaine-based zwitterionic monomers, including 3-(methacryloylamino) propyl-dimethyl-(3-sulfopropyl) ammonium hydroxide (MPDSAH) and 2-(methacryloyloxyethyl) ethyl-dimethyl-(3-sulfopropyl) ammonium (MEDSA) were successfully grafted from poly(vinylidene fluoride) (PVDF) hollow fiber membrane outside surface via chemical activation and atom transfer radical polymerization (ATRP). The ATRP time at 2 h under the 2 mol/L of zwitterionic monomers was the minimum period for the complete coverage of grafted sulfobetaine polymers on the PVDF membrane surface. The surface hydrophilicity of the sulfobetaine-modified PVDF membranes was significantly enhanced. The poly-MPDSAH-g-PVDF (GA: 247 mu g/cm2) and poly-MEDSA-g-PVDF membranes (GA: 338 mu g/cm2) efficiently resisted to the adsorption of both negative and positive charged proteins, and showed excellent anti-protein-fouling performance with flux recovery ratio (RFR) higher than 90% and total fouling (RT) less than 25% during the cyclic filtration of bovine serum albumin solution. After cleaned in membrane cleaning solution for 12 days, the grafted MPDSAH layer on PVDF membrane could maintain without change, however, the poly-MEDSA-g-PVDF membrane lost the grafted MEDSA layer. Therefore, the amide group of sulfobetaine, which made a great contribution to the higher hydrophilicity and stability, was significant in modifying the PVDF membrane for a stably anti-protein-fouling performance. (C) 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012