Hilton, E.M., Jhons, Y., Warren, N.J. orcid.org/0000-0002-8298-1417 et al. (1 more author) (2024) Polymers with quadruple hydrogen-bonding end groups: controlling molecular weight using a small molecule photoswitch. Polymer Chemistry, 15 (40). pp. 4115-4121. ISSN 1759-9954
Abstract
The molecular weight and topology of polymer chains is typically defined during their synthesis, after which these parameters remain fixed. This limitation has motivated efforts to develop reversibly reconfigurable polymers, which offer opportunities for advanced applications and/or efficient reprocessing. Herein, we report the preparation of a library of poly(methyl acrylate) (PMA) homopolymers and a poly(methyl methacrylate) (PMMA) homopolymer bearing pendant hydrogen bonding motifs (HBMs) which have the potential to generate reconfigurable materials. This approach includes the synthesis of alkyne-functional HBMs which were successfully coupled to an azide-functionalised RAFT agent via alkyne/azide “click” chemistry. The resulting ureidopyrimidinone (UPy) and amidonaphthyridine (NAP) RAFT agents could successfully be used to prepare PMA, but the attempt using the diamidonaphthyridine (DAN) RAFT agent was unsuccessful. In this example, a post-polymerisation technique was demonstrated as a viable alternative (in this case with a PMMA homopolymer). To demonstrate proof-of-concept that this can be achieved using a supramolecular approach: a small molecule photoswitch comprising ditopic azobenzene linked ureidopyrimidinone (UPy) was shown to effect reconfiguration of polymer molecular weight of DAN-functionalised PMMA under visible/UV light irradiation. In the cis (Z) photostationary state, intramolecular UPy·UPy homodimerization within the photoswitch was preferred, whereas in the trans (E) configuration, the need for UPy to satisfy its hydrogen-bonding requirements resulted in intermolecular DAN·UPy heterodimerization with the DAN motif of poly(methyl-methacrylate) resulting in a doubling of its molecular weight as observed by 1H DOSY NMR spectroscopy.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Royal Society of Chemistry 2024. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. (http://creativecommons.org/licenses/by/3.0/) |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Engineering (Sheffield) > School of Chemical, Materials and Biological Engineering |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 30 Sep 2024 13:32 |
Last Modified: | 25 Feb 2025 13:08 |
Status: | Published |
Publisher: | Royal Society of Chemistry (RSC) |
Refereed: | Yes |
Identification Number: | 10.1039/d4py00835a |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:217717 |