ABSTRACT:A series of copolymer microspheres of2-methacryloyloxyethyl phosphorylcholine (MPC) with comonomers (M) such as methyl-(MMA), ethyl-(EMA), n-butyl-(BMA), hexyl methacrylate (HMA), and styrene (St), poly(MPC-co-M), was prepared from the emulsifier-free emulsion copolymerization. From the kinetics of copolymerization of MPC and MMA, it was found that the initial rate of polymerization of MMA increased drastically in the presence of small amounts of MPC. A decrease in the yield of poly(MPC-co-MMA) microspheres and increase in that of its aggregates were observed with increasing content of the MPC moiety from Oto 10 mo!% in feed. The diameters of poly(MPC-co-M) microspheres were much smaller than those of corresponding poly(M) microspheres except for poly(MMA) microspheres. It was confirmed from XPS measurements that the MPC moiety is localized on the surface of particles. A series of poly(MPC-co-M) microspheres was found to absorb bovine serum albumin (BSA) less than the corresponding poly(M) microspheres as the control. It was concluded that the reduction of adsorbtion of BSA on poly(MPC-co-M) is dependent on the hydrophilicity of comonomer M and the MPC composition on the surface of particles.KEY WORDS Emulsion Copolymerization / 2-Methacryloyloxyethyl Phosphorylcholine / Vinyl Monomers/ Surface Modified Polymer Microspheres / XPS / Albumin Adsorption /

A series of copolymer microspheres of 2‐(acryloyloxy)ethylphosphorylcholine (APC) with comonomers (M) such as methyl (MMA), ethyl (EMA), butyl (BMA), hexyl methacrylate (HMA), and styrene (St), i. e. poly(APC‐co‐M) microspheres, were prepared by emulsifier‐free emulsion copolymerization. From the kinetics of the copolymerization, it was found that the initial rate of polymerization of St increases in the presence of small amounts of APC. The diameters of poly‐(APC‐co‐M) microspheres were much smaller than those of the corresponding homopolymer, poly(M). It was confirmed by X‐ray photoelectron spectroscopy measurements that the APC moiety is concentrated on the surface of the particles. A series of poly(APC‐co‐M) microspheres was found to adsorb both bovine serum albumin (Alb) and human serum γ‐globulin (Glo) less that the corresponding poly(M) microspheres as a control.