The ability of 2-vinyl-4,4-dimethyl-5-oxazolone (VDM), a highly reactive functional monomer, to produce block copolymers by reversible addition fragmentation chain transfer (RAFT) sequential polymerization with methyl acrylate (MA), styrene (S), and methyl methacrylate (MMA) was investigated using cumyl dithiobenzoate (CDB) and 2-cyanoisopropyl dithiobenzoate (CPDB) as chain transfer agents. The results show that PS-b-PVDM and PMA-b-PVDM well-defined block copolymers can be prepared either by polymerization of VDM from PS-and PMA-macroCTAs, respectively, or polymerization of S and MA from a PVDM-macroCTA. In contrast, PMMA-b-PVDM block copolymers with controlled molecular weight and low polydispersity can only be obtained by using PMMA as the macroCTA. Ab initio calculations confirm the experimental studies. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 5053-5062, 2010