Pure and Applied Chemistry

Abstract: In this paper, more than 70 years of cationic polymerization of isoprene (IP) are reviewed. Up to now, the controlled or living cationic polymerization of IP was never reported due to numerous side reactions, including chain transfer, cyclization, and cross-linking reactions that were very difficult to control. Cationic polyisoprenes (PIPs) are thus described to be mainly 1,4-trans with saturated/cyclized sequences. Although progress was made for their characterization due to many analysis techniques, cationic PIPs are still not yet fully characterized, particularly the saturated sequences. As a consequence, even if suggestions are proposed, polymerization mechanism is still not fully elucidated.