A novel ABA triblock copolymer comprising double-bond-containing poly(phenoxyallene) (PPOA) and polystyrene (PS) segments was synthesized by sequential conventional free radical polymerization and atom transfer radical polymerization (ATRP) via the site transformation strategy. A new bifunctional initiator containing azo and Br-containing ATRP initiating groups was prepared using 2-bromopropionyl chloride, hydroquinone, and 4,4'-azobis(4-cyanopentanoic acid) as starting materials. Conventional free radical homopolymerization of phenoxyallene with cumulated double bond was performed in toluene to provide a polyallene-based macroinitiator bearing ATRP initiating groups at both ends, which is stable under UV irradiation and free radical circumstances. PS-b-PPOA-b-PS triblock copolymer was then obtained by bulk ATRP of styrene initiated by PPOA-based macroinitiator. (C) 2017 Wiley Periodicals, Inc.