We report the synthesis and characterization of water soluble star copolymers based on 2-(N-dimethylamino)ethyl methacrylate, 2-(N-diethylamino)ethyl methacrylate, and 2-(N-morpholino)ethyl methacrylate monomers via group transfer polymerization. Ethylene glycol dimethacrylate was used as a branching agent. Highly cross-linked hetero-arm star copolymers were obtained with narrow molecular weight distributions and controlled molecular architectures. Star copolymers were obtained in good yield with a monomer/branching agent at the appropriate mole ratio without macrogelation. Additionally, analog linear diblock copolymers with similar comonomer ratios were also synthesized to make comprehension. Star copolymers had lower viscosities compared to linear analogs at pH 8.1. Critical micelle concentration and critical micellization pH values were also determined for these star copolymers and compared to linear diblock copolymers. All polymers were characterized using gel permeation chromatography combined with a light scattering and a refractive index detectors and H-1 NMR spectroscopy, to determine the molecular weights, molecular weight distributions and comonomer compositions, respectively. Solution behaviors of the polymers were also analyzed with a viscometer, densitometer, and surface tensiometer. (C) 2015 Elsevier Ltd. All rights reserved.