The atom transfer radical polymerization (ATRP) and reversible addition-fragmentation chain transfer (RAFT) of acrylates (methyl acrylate and butyl acrylate) with allyl butyl ether (ABE) were investigated. Well-defined copolymers containing almost 20 mol % ABE were obtained with ethyl-2-bromoisobutyrate as an initiator. Narrow molar mass distributions (MMDs; polydispersity index less than or equal to 1.3) were obtained from the ATRP experiments, and they suggested conventional ATRP behavior, with no peculiarities caused by the incorporation of ABE. The comparable free-radical (co)polymerizations resulted in broad MMDs. Increasing the fraction of ABE in the monomer feed led to an increase in the level of incorporation of ABE in the copolymer, at the expense of the overall conversion. Similarly, RAFT copolymerizations with S,S'bis(alpha,alpha'-dimethyl-alpha"-acetic acid)trithiocarbonate also resulted in excellent control of the polymerization with a significant incorporation of ABE within the copolymer chains. The formation of the copolymer was confirmed with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). From the obtained MALDI-TOF MS spectra for the ATRP and RAFT systems, it was evident that several units of ABE were incorporated into the polymer chain. This was attributed to the rapidity of the cross-propagation of ABE-terminated polymeric radicals with acrylates. This further indicated that ABE was behaving as a comonomer and not simply as a chain-transfer agent under the employed experimental conditions. (C) 2004 Wiley Periodicals, Inc.