Unexpected switching of the photogelation chemistry when cross-linking poly(2-oxazoline) copolymers

Dargaville, Tim R., Lava, Kathleen, Verbraeken, Bart, & Hoogenboom, Richard (2016) Unexpected switching of the photogelation chemistry when cross-linking poly(2-oxazoline) copolymers. Macromolecules, 49(13), pp. 4774-4783.

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Abstract

The photohydrogelation reaction of functional poly(2-oxazoline)s can be significantly accelerated by the presence of weak hydrophobic interactions. Here we describe the synthesis and cross-linking of water-soluble poly(2-oxazoline) copolymers containing vinyl groups in the side chains by copolymerizing 2-methyl-2-oxazoline and 2-undecenyl-2-oxazoline or 2-(3-butenyl)-2-oxazoline. An improved synthetic pathway to the 2-(3-butenyl)-2-oxazoline monomer based on α-deprotonation of 2-methyl-2-oxazoline is also included. When exposed to radical thiol–ene conditions in the presence of dithiothreitol in water, all of the copolymers produced homogeneous hydrogels, but the nature of the copolymers greatly influenced the cross-linking kinetics. The polymers with the vinyl groups on short alkyl chains cured slowly, and the physical properties of the hydrogels were strongly dependent on the molar ratio of thiol and ene groups. Conversely, the polymers with the vinyl groups on long alkyl chains cured extremely rapidly, whereby the process was nearly independent of the thiol concentration. A model of hydrophobic interactions actually enhancing cure kinetics, but at the expense of the thiol–ene reaction, is proposed.

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ID Code: 97814
Item Type: Journal Article
Refereed: Yes
Keywords: copolymer, hydrogel, photocuring, poly(2-oxazoline), thiol-ene
DOI: 10.1021/acs.macromol.6b00167
ISSN: 1520-5835
Subjects: Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300)
Australian and New Zealand Standard Research Classification > CHEMICAL SCIENCE (030000) > MACROMOLECULAR AND MATERIALS CHEMISTRY (030300) > Chemical Characterisation of Materials (030301)
Divisions: Current > Schools > School of Chemistry, Physics & Mechanical Engineering
Past > QUT Faculties & Divisions > Faculty of Science and Technology
Current > Institutes > Institute of Health and Biomedical Innovation
Funding:
Copyright Owner: Copyright 2016 American Chemical Society
Copyright Statement: This document is the Accepted Manuscript version of a Published Work that appeared in final form in Macromolecules, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/abs/10.1021/acs.macromol.6b00167
Deposited On: 01 Aug 2016 00:53
Last Modified: 07 Aug 2016 04:31

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