Facile synthesis of poly(N-vinyl pyrrolidone) block copolymers with “more-activated” monomers by using photoinduced successive RAFT polymerization†
It has still been a great challenge in polymer chemistry to synthesize well-defined block copolymers from both “more-activated” monomer (MAM) and “less-activated” monomer (LAM). Herein, a novel xanthate O-phenyl-S-[1-(phenylethyl)] dithiocarbonate (PXPE) was synthesized and used to mediate the successive polymerizations of a series of MAMs (e.g., butyl acrylate (BA), methyl acrylate (MA) and styrene (St)) and N-vinyl pyrrolidone (NVP) by using a single method under irradiation with UV or visible light. The well-defined PMAM-b-PNVP block copolymers (e.g., PBA-b-PNVP, PMA-b-PNVP, PS-b-PNVP) were obtained with narrow molecular weight distributions (Mw/Mn ≤ 1.37). The living features of the polymerization were demonstrated by the linear increase of molecular weights with monomer conversion. Moreover, the components in this polymerization system were simple and no extra initiators or catalysts were required, which brought about great advantages for the potential application of this technique.