Synthesis and characterization of well-defined ABC-type triblock copolymers via atom transfer radical polymerization and stable free-radical polymerization

An asymmetric difunctional initiator 2-phenyl-2-[(2,2,6,6 tetramethylpiperidino)oxy] ethyl 2-bromo propanoate (1) was used for the synthesis of ABC-type methyl methacrylate (MMA)-tert-butylacrylate (tBA)-styrene (St) triblock copolymers via a combination of atom transfer radical polymerization (ATRP) and stable free-radical polymerization (SFRP). The ATRP-ATRP-SFRP or SFRP-ATRP-ATRP route led to ABC-type triblock copolymers with controlled molecular weight and moderate poly-dispersity (M_w/M_n < 1.35). The block copolymers were characterized by gel permeation chromatography and ¹H NMR. The retaining chain-end functionality and the applying halide exchange afforded high blocking efficiency as well as maintained control over entire routes.