A star polymer composed of three poly(ethylene glycol) (PEG) arms and one poly(N,N-dimethyl acrylamide) (PDMA) arm (PEG3PDMA) was synthesized by amidation and atom-transfer radical polymerization. The structure of PEG3PDMA was confirmed by 1H-NMR and gel permeation chromatography results. The surface adsorption and protein-resistance behaviors of the star polymer PEG3PDMA, diblock copolymer PEGPDMA, and homopolymer PEG were investigated by a quartz crystal microbalance with dissipation. The results indicate that the PEG3PDMA coating could reduce protein adsorption to 13% at least, more effectively than the PEGPDMA coating; this indicated that the protein-resistance properties depended on the PEG chain density and surface coverage. If PEG3PDMA were to be used as the physical coating in capillary zone electrophoresis, it could yield a well-suppressed eletroosmotic flow with greater stability and separate proteins with a lower relative standard deviration (RSD) of protein migration time and a higher separation efficiency than a bare fused-silica capillary in a broad pH range. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013