Three well-defined diblock copolymers of poly(methyl methacrylate-b-methacrylic acid)(P(MMA-b-MAA))were synthesized using atom transfer radical polymerization method and varying poly(methacrylic acid)(PMAA)chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process.Membrane morphologies were observed by scanning electron microscopy(SEM),and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy(XPS).Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes.It was found that,the blend membranes containing longer PMAA arm length showed lower static protein adsorption,higher water permeation flux and better protein solution flux recovery. These copolymers (CMAA) were synthesized using atom transfer radical polymerization method and varying poly (methacrylic acid) (PMAA) chain lengths. These copolymers were blended with PVC to fabricate porous membranes via phase inversion process. Membrane morphologies were observed by scanning electron microscopy (SEM), and chemical composition changes of the membrane surfaces were measured by X-ray photoelectron spectroscopy (XPS). Static and dynamic protein adsorption experiments were used to evaluate antifouling properties of the blend membranes. It was found that the blend membranes containing longer PMAA arm length showed lower static protein adsorption, higher water permeation flux and better protein solution flux recovery.