Ring-expansion/contraction radical crossover reactions of cyclic alkoxyamines: A mechanism for ring expansion-controlled radical polymerization

Atsushi Narumi, Tetsuya Kobayashi, Masatsugu Yamada, Wolfgang H. Binder, Keigo Matsuda, Montaser Shaykoon Ahmed Shaykoon, Kazushi Enomoto, Moriya Kikuchi, Seigou Kawaguchi

研究成果: Article査読

3 被引用数 (Scopus)

抄録

Macrocyclic polymers present an important class of macromolecules, displaying the reduced radius of gyration or impossibility to entangle. A rare approach for their synthesis is the ring expansion-controlled radical "vinyl" polymerization, starting from a cyclic alkoxyamine. We here describe ring-expansion radical crossover reactions of cyclic alkoxyamines which run in parallel to chain-propagation reactions in the polymerization system. The radical crossover reactions extensively occurred at 105-125 °C, eventually producing high molecular weight polymers with multiple inherent dynamic covalent bonds (NOC bonds). A subsequent ring-contraction radical crossover reaction and the second ring-expansion radical crossover reaction are also described. The major products for the respective three stages were shown to possess cyclic morphologies by the molecular weight profiles and the residual ratios for the NOC bonds (ϕ in %). In particular, the high ϕ values ranging from ca. 80% to 98% were achieved for this cyclic alkoxyamine system. This result verifies the high availability of this system as a tool demonstrating the ring-expansion "vinyl" polymerization that allows them to produce macrocyclic polymers via a one-step vinyl polymerization.

本文言語English
論文番号638
ジャーナルPolymers
10
6
DOI
出版ステータスPublished - 2018 6 8
外部発表はい

ASJC Scopus subject areas

  • 化学 (全般)
  • ポリマーおよびプラスチック

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