Synthesis of amphiphilic star block copolymers via diethyldithiocarbamate-mediated living radical polymerization

(AB)(f) star block copolymers were synthesized by the radical polymerization of a poly(t-butyl acrylate)-block-poly(methyl methacrylate) diblock macroinitiator with ethylene glycol dimethacrylate in methanol under UV irradiation. Diblock macroinitiators were prepared by diethyldithiocarbamate-mediated sequential living radical copolymerization initiated by (4-cyano-4-diethyldithiocarbamyl)pentanoic acid under UV irradiation. The arm number (f) was controlled by the variation of the initial concentration of the diblock initiator. It was found from light scattering data that such star block copolymers (f >= 344) not only took a spherical shape but also formed a single molecule in solution. Subsequently, we derived amphiphilic [arm: poly(acrylic acid)-block-poly(methyl metbacrylate)] star block copolymers by the hydrolysis of poly(t-butyl acrylate) blocks. These amphiphilic star block copolymers were soluble in water because the external blocks were composed of bydrophilic poly(acrylic acid) chains.