Amphiphilic poly(ε-caprolactone)-block-poly(N-vinyl pyrrolidone) (PCL-b-PNVP) copolymer was synthesized by nitroxide-mediated radical polymerization of N-vinyl pyrrolidione (NVP) at the mediation of PCL with terminated-nitroxide radical group (PCL-T)|PCL-T has been prepared by the ring-opening polymerization of ε-CL with 4-hydroxy-2,2,6,6-tetramethyl-piperidinooxy (HTEMPO) as initiator. The hydrogen nuclear magnetic resonance (¹H NMR), electron spin resonance (ESR), fourier transform infrared spectroscopy (FTIR) and gel permeation chromatography (GPC) were employed to characterize the structure of the polymers. The self-assembly behavior of the copolymers in aqueous media was studied by fluorescence spectra, dynamic light scanning (DLS) and transmission electron microscope (TEM). The results showed that the well-defined PCL-b-PNVP copolymer could be synthesized by combination of ring-opening polymerization and nitroxide-mediated radical polymerization, and the obtained copolymer could be self-assembled into well-dispersed core-shell spherical micelles with a size of 100 nm in aqueous solution. Moreover, the copolymer displayed good biocompatibility and could be acted as the hydrophobic drug carrier.

Key words: amphiphilic block copolymer, poly(N-vinyl pyrrolidone), poly(ε-caprolactone), micelles