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Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization
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-ex...
Autores principales: | , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
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MDPI
2018
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6404036/ https://www.ncbi.nlm.nih.gov/pubmed/30966672 http://dx.doi.org/10.3390/polym10060638 |
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author | Narumi, Atsushi Kobayashi, Tetsuya Yamada, Masatsugu Binder, Wolfgang H. Matsuda, Keigo Shaykoon, Montaser Shaykoon Ahmed Enomoto, Kazushi Kikuchi, Moriya Kawaguchi, Seigou |
author_facet | Narumi, Atsushi Kobayashi, Tetsuya Yamada, Masatsugu Binder, Wolfgang H. Matsuda, Keigo Shaykoon, Montaser Shaykoon Ahmed Enomoto, Kazushi Kikuchi, Moriya Kawaguchi, Seigou |
author_sort | Narumi, Atsushi |
collection | PubMed |
description | 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. |
format | Online Article Text |
id | pubmed-6404036 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2018 |
publisher | MDPI |
record_format | MEDLINE/PubMed |
spelling | pubmed-64040362019-04-02 Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization Narumi, Atsushi Kobayashi, Tetsuya Yamada, Masatsugu Binder, Wolfgang H. Matsuda, Keigo Shaykoon, Montaser Shaykoon Ahmed Enomoto, Kazushi Kikuchi, Moriya Kawaguchi, Seigou Polymers (Basel) Communication 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. MDPI 2018-06-08 /pmc/articles/PMC6404036/ /pubmed/30966672 http://dx.doi.org/10.3390/polym10060638 Text en © 2018 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/). |
spellingShingle | Communication Narumi, Atsushi Kobayashi, Tetsuya Yamada, Masatsugu Binder, Wolfgang H. Matsuda, Keigo Shaykoon, Montaser Shaykoon Ahmed Enomoto, Kazushi Kikuchi, Moriya Kawaguchi, Seigou Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title | Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title_full | Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title_fullStr | Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title_full_unstemmed | Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title_short | Ring-Expansion/Contraction Radical Crossover Reactions of Cyclic Alkoxyamines: A Mechanism for Ring Expansion-Controlled Radical Polymerization |
title_sort | ring-expansion/contraction radical crossover reactions of cyclic alkoxyamines: a mechanism for ring expansion-controlled radical polymerization |
topic | Communication |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6404036/ https://www.ncbi.nlm.nih.gov/pubmed/30966672 http://dx.doi.org/10.3390/polym10060638 |
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