journal article

Journal Article

ACS Macro Letters. 2020, 9(1), p. 77-83

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

American Chemical Society

English

2020-01-21

https://doi.org/10.1021/acsmacrolett.9b00874

Higuchi M., Kanazawa A., Aoshima S.. Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester. ACS Macro Letters 9, 77 (2020); https://doi.org/10.1021/acsmacrolett.9b00874.

Cationic copolymerization of different types of monomers, 4-hydroxybutyl vinyl ether (HBVE) and ϵ-caprolactone (CL), was explored using EtSO3H as an acid catalyst, producing copolymers with a remarkably wide variety of compositions and sequences. In the initial stage of the reaction, HBVE was unexpectedly isomerized to 2-methyl-1,3-dioxepane (MDOP), followed by concurrent copolymerization of MDOP and CL via active chain end and activated monomer mechanisms, respectively. The compositions and sequences of the copolymers were tunable, depending on the initial monomer concentrations. Moreover, a unique method was developed for transforming a copolymer with no CL homosequences into an "alternating" copolymer by removing MDOP from the system using a vacuum pump. This was achieved by the tandem reactions of depolymerization (unzipping) and random transacetalization (scrambling) under thermodynamic control. Specifically, the unzipping of HBVE homosequences proceeded at the oxonium chain end until a nondissociable ester bond emerged next to the chain end, while the scrambling of the main chain via transacetalization transferred midchain HBVE homosequences into the polymer chain end.

This document is the Accepted Manuscript version of a Published Work that appeared in final form in ACS Macro Letters, © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work seehttps://doi.org/10.1021/acsmacrolett.9b00874

100924

Tandem Unzipping and Scrambling Reactions for the Synthesis of Alternating Copolymers by the Cationic Ring-Opening Copolymerization of a Cyclic Acetal and a Cyclic Ester

American Chemical Society

English

2020-01-21

ACS Macro Letters

9

1

77

83

https://doi.org/10.1021/acsmacrolett.9b00874

https://hdl.handle.net/11094/100924