Polymerization of 2-methacryloyloxyethyl phosphorylcholine (MPC) was kinetically investigated in ethanol using dimethyl 2,2ะ-azobisisobutyrate (MAIB) as initiator. The overall activation energy of the homogeneous polymerization was calculated to be 71 kJ/mol. The polymerization rate (R p ) was expressed by R p ฯญ k[MAIB] 0.54ฯฎ0.05 [MPC] 1.8ฯฎ0.1 . The higher dependence of R p on the monomer concentration comes from acceleration of propagation due to monomer aggregation and also from retardation of termination due to viscosity effect of the MPC monomer. Rate constants of propagation (k p ) and termination (k t ) of MPC were estimated by means of ESR to be k p ฯญ 180 L/mol โ
s and k t ฯญ 2.8 ฯซ 10 4 L/mol โ
s at 60 ยฐC, respectively. Because of much slower termination, R p of MPC in ethanol was found at 60 ยฐC to be 8 times that of methyl methacrylate (MMA) in benzene, though the different solvents were used for MPC and MMA. Polymerization of MPC with MAIB in ethanol was accelerated by the presence of water and retarded by the presence of benzene or acetonitrile. Poly(MPC) showed a peculiar solubility behavior; although poly(MPC) was highly soluble in ethanol and in water, it was insoluble in aqueous ethanol of water content of 7.4 -39.8 vol %. The radical copolymerization of MPC (M 1 ) and styrene (St) (M 2 ) in ethanol at 50 ยฐC gave the following copolymerization parameters similar to those of the copolymerization of MMA and St; r 1 ฯญ 0.39, r 2 ฯญ 0.46, Q 1 ฯญ 0.76, and e 1 ฯญ ฯฉ0.51.