Controlled Cationic Copolymerization of Vinyl Monomers and Cyclic Acetals via Concurrent Vinyl-Addition and Ring-Opening Mechanisms

• Published in: Macromolecules Vol. 49; no. 19; pp. 7184 - 7195
• Main Authors: Shirouchi, Tomoka, Kanazawa, Arihiro, Kanaoka, Shokyoku, Aoshima, Sadahito
• Format: Journal Article
• Language: English
• Published: American Chemical Society 11.10.2016
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.6b01565

Vinyl monomers and cyclic acetals were demonstrated to copolymerize with sufficient crossover propagation reactions in a controlled manner via the generation of long-lived species. Such unusual propagation reactions, mediated by the active species derived from different types of monomers, were shown to require an appropriate dormant–active equilibrium, achieved via the elaborate design of the initiating systems. The controlled copolymerization of 2-chloroethyl vinyl ether (CEVE) and 1,3-dioxepane (DOP) proceeded using SnCl4 as a catalyst in conjunction with ethyl acetate and 2,6-di-tert-butyl­pyridine, yielding multiblock-like copolymers as a result of several rounds of crossover reactions per chain. Under the same conditions, when 2-methyl-1,3-dioxolane (MDOL) was used instead of DOP, the polymerization proceeded in a highly controlled manner and involved more frequent crossover reactions. In addition, MDOL underwent almost no homopropagation reactions, unlike DOP. The nature of the cyclic acetal-derived propagating species is most likely responsible for the difference in the copolymerization behavior. Long-lived species were also generated in the copolymerization of styrene and 1,3-dioxolane (DOL), although measurable amounts of cyclic oligomers were produced via backbiting reactions.