A novel thermosensitive amphiphilic copolymer comprised of two hydrophobic poly(oleic acid) (POA) segments and one hydrophilic poly(N-isopropylacrylamide) (PNIPAAm) segment was designed and synthesized. The structure of the copolymer was confirmed as Y-shaped by FTIR, 1H NMR, and SEC-MALLS analysis. A cytotoxicity study shows that the P(OA-Y-NIPAAm) copolymer exhibits good biocompatibility. The copolymer may self-assemble into micelles in water, with the hydrophobic POA segments at the cores of micelles and the hydrophilic PNIPAAm segments as the outer shells. The resulting micelles demonstrate temperature sensitivity with a lower critical solution temperature (LCST) of 31.5 degrees C and a critical micelle concentration (CMC) of 12.6 mg L(-1). Transmission electron microscopy (TEM) shows that the micelles exhibit a nanospheric morphology within a narrow size range of approximately 10-30 nm. A study of controlled release reveals that the self-assembled micelles have great potential as drug carriers.