New hydroxyl-terminated amphiphilic block copolymers (HO-ABPs) having pendant t-butyl groups for pH-responsiveness and terminal OH groups for bioconjugation are reported. These HO-ABPs consist of hydrophilic poly(oligo(ethylene oxide) monomethyl ether methacrylate) and hydrophobic poly(t-butyl methacrylate) blocks and were synthesized by a consecutive atom transfer radical polymerization in the presence of an OH-terminated bromine initiator. Aqueous self-assembly of HO-ABPs resulted in colloidally stable micellar aggregates being capable of encapsulating hydrophobic guest molecules. They were nontoxic to cells and destabilized in response to low pH. A facile bioconjugation of HO-ABP micelles for active targeting is demonstrated by conjugation with biotin (vitamin H) and competitive assay exhibiting >93% ABP chains conjugated with biotin in each micelle. (c) 2013 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013, 51, 1620-1629