A poly(ethylene oxide)-block-poly(dimethylamino ethyl methacrylate) block copolymer (PEO-b-PDMAEMA) bearing an amino moiety at the PEO chain end was synthesized by a one-pot sequential oxyanionic polymerization of ethylene oxide (EO) and dimethylamino ethyl methacrylate (DMAEMA), followed by a coupling reaction between its PEO amino and a biotin derivative. The polymers were characterized with H-1 NMR spectroscopy and gel permeation chromatography. Activated biotin, biotin-NHS (N-hydroxysucci-nimide), was used to synthesize biotin-PEO-PDMAEMA. In aqueous media, the solubility of the copolymer was temperature- and pH-sensitive. The particle size of the micelle formed from functionalized block copolymers was determined by dynamic light scattering. (c) 2006 Wiley Periodicals, Inc.