Polyallene-based amphiphilic triblock copolymer via successive free radical polymerization and ATRP†
A new ABA amphiphilic triblock copolymer, comprising double-bond-containing poly(phenoxyallene) (PPOA) and poly(oligo(ethylene glycol) methyl ether methacrylate) (POEGMM) segments, was synthesized by a combination of conventional free radical polymerization, atom transfer radical polymerization (ATRP), and the site transformation strategy. A bifunctional initiator containing azo and Br-containing ATRP initiating groups was employed to initiate conventional free radical homopolymerization of phenoxyallene with a cumulated double bond to give a PPOA-based macroinitiator (Br-PPOA-Br) bearing ATRP initiating groups at both ends. Next, ATRP of OEGMM monomer was initiated by Br-PPOA-Br to provide the desired POEGMM-b-PPOA-b-POEGMM triblock copolymer. The critical micelle concentration of POEGMM-b-PPOA-b-POEGMM amphiphilic copolymer in aqueous solution was determined by fluorescence spectroscopy. The amphiphilic triblock copolymer could self-assemble into wormlike and spherical micelles in aqueous media. POEGMM-b-PPOA-b-POEGMM triblock copolymer can also be used as the stabilizer for the aqueous polymerization of styrene and methyl methacrylate.