SYNTHESIS OF GRAFT-COPOLYMERS HAVING PHOSPHOLIPID POLAR GROUP BY MACROMONOMER METHOD AND THEIR PROPERTIES IN WATER

Water-soluble graft copolymers with phospholipid polar group were synthesized by the macromonomer method and their properties in water were investigated by surface tension and fluorescence spectroscopic measurements. At first, 2-methacryloyloxyethyl phosphorylcholine (MPC) was polymerized in the presence of 3-mercapt propionic acid as a chain transfer agent and carboxyl group-terminated oligo (MPC) was obtained. The oligo (MPC) reacted with glycidyl methacrylate to convert the carboxyl group to a polymerizable methacryloyl group. The MPC macromonomer obtained was copolymerized with hydrophobic n-butyl methacrylate (BMA) and a graft copolymer was obtained. The graft copolymer, poly(MPC-graft-BMA), was water-soluble when the MPC unit mole fraction was above 0.40. The surface tension of the aqueous solution of poly(MPC-graft-BMA) did not depend on the polymer concentration below 0.1 wt %. This tendency was the same as that which appeared in aqueous poly (MPC) solution. The fluorescence intensity of hydrophobic probes observed in an aqueous solution of the poly(MPC-graft-BMA) was also the same level as that observed in the case of poly(MPC). These results clearly indicated that the poly(MPC-graft-BMA) took a domain structure like micelle in water, i.e., the hydrophobic poly(BMA) backbone was in the core part and the hydrophilic poly (MPC) chain formed the shell part of the micelle. (C) 1994 John Wiley & Sons, Inc.