The well-defined, thermosensitive and biodegradable graft copolymers, poly(N-isopropylacrylamide)-b-[2-hydroxyethyl methacrylate-poly(epsilon-caprolactone)](n) (PNIPAAm-b-(HEMA-PCL)(n)) (n = 3 or 9), were synthesized by combining reversible addition-fragmentation chain transfer polymerization and macromonomer method. The copolymers were able to self-assemble into micelles in water with low critical micellar concentration and demonstrated temperature sensitivity with a lower critical solution temperature at around 36 degrees C. Transmission electron microscopy shows that the micelles exhibit a nanosized spherical morphology within a size range of 30-100 nm. The PNIPAAm-b-(HEMA-PCL)(3) copolymer exhibited biodegradation and low cytotoxicity. The paclitaxel-loaded PNIPAAm-b-(HEMA-PCL)(3) micelles displayed thermosensitive controlled release behavior, which indicates potential as drug carriers. (c) 2007 Wiley Periodicals, Inc.