The reversible addition fragmentation chain transfer (RAFT) polymerization of five active ester monomers based on 4-vinylbenzoic acid had been investigated. Pentafluorophenyl 4-vinylbenzoate could be polymerized under RAFT conditions yielding polymers with very good control over molecular weight and narrow molecular weight distributions. Following the synthesis of diblock copolymers consisting of polystyrene, polypentafluorostyrene, poly(4-octylstyrene), or poly(4-acetoxy styrene) as an inert block and poly(pentafluorophenyl 4-vinylbenzoate) as a reactive block was successfully performed. The diblock copolymer poly(pentafluoro styrene)-blockpoly(pentafluorophenyl 4-vinylbenzoate) had been analyzed by F-19 NMR spectroscopy in solution, demonstrating the synthetic potential of pentafluorophenyl 4-vinylbenzoate as an extremely valuable monomer for the synthesis of highly functionalized polymeric architectures. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1696-1705,2009