A new azide-functionalized xanthate, S-(4-azidomethylbenzyl) O-(2-methoxyethyl) xanthate, was synthesized and used to mediate the reversible addition fragmentation chain transfer polymerization of vinyl acetate. The polymerization was demonstrated to be controlled, and well-defined PVAc with alpha-azide, omega-xanthate groups were obtained, the xanthate groups of which were further removed by radical-induced reduction with lauroyl peroxide in the presence of excess 2-propanol. Hydrolysis of alpha-azide-terminated PVAc (N-3-PVAc) led to the formation of the corresponding alpha-azide-terminated PVA (N-3-PVA). Finally, end-modification of N3-PVA by click chemistry with alkyne-end-capped poly(caprolactone) (A-PCL), alkynyl-mannose, and alkynyl-pyrene was carried out to obtain a new block copolymer PCL-b-PVA, and two PVA with mannose or pyrene as the end functional groups. The polymers were characterized by gel permeation chromatography, H-1 NMR spectroscopy, and FTIR. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4494-4504, 2009