Novel tri-armed star polystyrene-block-poly(N-isopropylacrylamide) block copolymers with trimesic acid as central molecules were synthesized by successive two-step atom transfer radical polymerization, and confirmed by Fourier-transform infrared spectra, H-1 nuclear magnetic resonance, and laser light scattering gel chromatography system. The copolymers could self-assemble into spherical core-shell micelles in aqueous media independent on drug loading. Physicochemical properties of the blank and drug-loaded micelles were examined by surface tension, fluorescence spectroscopy, UV-vis, transmission electron microscope, and dynamic light scattering measurements. The copolymer micelles exhibited thermo-triggered phase transition, with low critical solution temperature of 33.7 and 34.6 degrees C, varying with copolymer compositions. The critical aggregate concentrations were 11.62 and 47.61 mg L-1, and hydrodynamic diameters from 200 to 220 nm. Water-insoluble 10-hydroxycamptothecine was encapsulated into the micelle aggregates to investigate the change in the resulting physicochemical parameters, thermo-triggered in vitro drug release, and the applicability as drug targeting release carriers. MTT assays were carried out to uncover cytotoxicity of the newly developed micelle-based drug formulations. (c) 2014 American Institute of Chemical Engineers AIChE J, 61: 35-45, 2015