A novel block copolymer, poly(epsilon-caprolactone)-b-poly(4-vinyl pyridine), was synthesized with a bifunctional initiator strategy. Poly(e-caprolactone) prepolymer with a 2,2,6,6-tetramethylpiperidinyloxy (TEMPO) end group (PCLT) was first obtained by coordination polymerization, which showed a controlled mechanism in the process. By means of ultraviolet spectroscopy and electron spin resonance spectroscopy, the TEMPO moiety was determined to be intact in the polymerization. The copolymers were then obtained by the controlled radical polymerization of 4-vinyl pyridine in the presence of PCLT. The desired block copolymers were characterized by gel permeation chromatography, Fourier transform infrared spectroscopy, and NMR spectroscopy in detail. Also, the effects of the molecular weight and concentration of PCLT on the copolymerization were investigated. (C) 2004 Wiley Periodicals, Inc.