A series of well-defined amphiphilic triblock copolymers, poly(ethylene glycol)-b-poly(tert-butyl acrylate)-b-poly(2-hydroxyethyl methacrylate) (PEG-b-PtBA-b-PHEMA), were synthesized via successive atom transfer radical polymerization (ATRP). ATRP of tBA was first initiated by PEG-Br macroinitiator using CuBr/N,N,N',N",N"-pentamethyldiethylenetriamine as catalytic system to give PEG-b-PtBA diblock copolymer. This copolymer was then used as macroinitiator to initiate ATRP of HEMA, which afforded the target triblock copolymer, PEG-b-PtBA-b-PHEMA. The critical micelle concentrations of obtained amphiphilic triblock copolymers were determined by fluorescence spectroscopy using N-phenyl-1-naphthylamine as probe. The morphology and size of formed aggregates were investigated by transmission electron microscopy and dynamic light scattering, respectively. Finally, an acid-sensitive PEG-b-PtBA-b-P(HEMA-CAD) prodrug via cis-aconityl linkage between doxorubicin and hydroxyls of triblock copolymers with a high drug loading content up to 38%, was prepared to preliminarily explore the application of triblock copolymer in drug delivery. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012