Solution properties of hyperbranched polymers and synthetic application for amphiphilic star-hyperbranched copolymers by grafting from hyperbranched macroinitiator

摘要

Hyperbranched polystyrenes (PS) were prepared by living radical photopolymerization of N,N-diethyldithiocarbamoylmethylstyrene (DTCS) as an inimer under UV irradiation. Branched PS with an average chain length between branching points of four styrene units was also prepared by living radical copolymerization of DTCS with styrene. The ratio of radius of gyration to hydrodynamic radius R_G/R_H for these hyperbranched polymers was in the range 0.82-0.89 in toluene. The translational diffusion coefficient D(C) showed a constant value in the range of 0-14 X 10~(-3) g ml~(-1) in toluene. It was found from these dilute solution properties that hyperbranched PSs formed a unimolecular structure even in a good solvent because of their compact nature. These hyperbranched PSs exhibited large amounts of photofunctional carbamate (DC) groups on their outside surfaces. Subsequently, we derived amphiphilic star-hyperbranched copolymers by grafting from hyperbranched macroinitiator with 1-vinyl-2-pyrrolidinone. These star-hyperbranched copolymers were soluble in water and methanol.