Synthesis of block copolymer nano-assemblies via ICAR ATRP and RAFT dispersion polymerization: how ATRP and RAFT lead to differences

Abstract

Block copolymer nano-assemblies were synthesized via initiators for continuous activator regeneration atom transfer radical polymerization (ICAR ATRP) dispersion polymerization employing the CuBr₂/tris(2-pyridylmethyl)amine catalyst in an alcoholic solvent at a relatively low temperature of 45 °C. The typical poly(ethylene glycol)-block-polystyrene (PEG-b-PS) nano-assemblies synthesized via ICAR ATRP dispersion polymerization are compared with those synthesized via RAFT dispersion polymerization under other similar conditions. It is found that the PEG₄₅-b-PS nano-assemblies, e.g., including lamellas, vesicles and vesicular clusters, synthesized via ICAR ATRP dispersion polymerization have very complicated morphologies, which are different from those synthesized via RAFT dispersion polymerization. The reasons leading to the differences are investigated, and it is conclusively supposed that the high Đ of the synthesized BCPs and the salt of the copper catalyst used in ICAR ATRP dispersion polymerization should be involved. This low temperature initiated ICAR ATRP dispersion polymerization is believed to be a valid method to prepare block copolymer nano-assemblies through polymerization-induced self-assembly.