Homo and copolymerization of isoprene (IP) with small amounts (1% wt) of glycidyl methacrylate) were conducted using the reversible addition-fragmentation chain-transfer process (RAFT) at 125 degrees C in a solution polymerization process using toluene as solvent. Suitable reaction conditions to avoid Diels-Alder dimerization of IP and crosslinking were determined; and 4-cyano-4-[(dodecylsulfanylthiocarbonyl)sulfanyl] pentanoic acid was found to be the best transfer agent among those tested. Theoretical calculations were used to understand why some RAFT agents work better than others in these polymerizations. Molecular weights M-n higher than 100,000 Da were reached by successive chain extension experiments, confirming the livingness of the intermediate polymers. All the successful polymerizations yielded average molar masses (M-n) of about 75% compared to the theoretical M-n (M-n,M-theo) depending on the agent used for control. The dispersity () ranged from 1.20 to 1.70 being a function of the control agent. The polymers were characterized by FTIR spectroscopy, H-1 NMR, and gel permeation chromatography. (c) 2018 Wiley Periodicals, Inc.