Deane, O.J., Jennings, J., Neal, T.J. et al. (3 more authors) (2021) Synthesis and aqueous solution properties of shape-shifting stimulus-responsive diblock copolymer nano-objects. Chemistry of Materials, 33 (19). pp. 7767-7779. ISSN 0897-4756
Abstract
We report the synthesis of poly(N-(2-acryloyloxyethyl)pyrrolidone)-poly(4-hydroxybutyl acrylate) (PNAEP85-PHBAx) diblock copolymer nano-objects via reversible addition–fragmentation chain transfer (RAFT) aqueous dispersion polymerization of 4-hydroxybutyl acrylate (HBA) at 30 °C using an efficient two-step one-pot protocol. Given the relatively low glass transition temperature of the PHBA block, these nano-objects required covalent stabilization prior to transmission electron microscopy (TEM) studies. This was achieved by core crosslinking using glutaraldehyde. TEM analysis of the glutaraldehyde-fixed nano-objects combined with small-angle X-ray scattering (SAXS) studies of linear nano-objects confirmed that pure spheres, worms or vesicles could be obtained at 20 °C in an acidic aqueous solution by simply varying the mean degree of polymerization (x) of the PHBA block. Aqueous electrophoresis, dynamic light scattering and TEM studies indicated that raising the dispersion pH above the pKa of the terminal carboxylic acid group located on each PNAEP chain induced a vesicle-to-sphere transition. 1H NMR studies of linear PNAEP85-PHBAx nano-objects indicated a concomitant increase in the degree of partial hydration of PHBA chains on switching from pH 2-3 to pH 7-8, which is interpreted in terms of a surface plasticization mechanism. Rheological and SAXS studies confirmed that the critical temperature corresponding to the maximum worm gel viscosity could be tuned from 2 to 50 °C by adjusting the PHBA DP. Such tunability is expected to be useful for potential biomedical applications of these worm gels.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2021 The Authors. Published by American Chemical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (http://creativecommons.org/licenses/by/4.0) |
Keywords: | Vesicles; RAFT polymerization; Copolymers; Colloids; Transmission electron microscopy |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > Department of Chemistry (Sheffield) |
Funding Information: | Funder Grant number ENGINEERING AND PHYSICAL SCIENCE RESEARCH COUNCIL EP/R003009/1 Engineering and Physical Sciences Research Council EP/L016281/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 11 Oct 2021 13:54 |
Last Modified: | 10 Mar 2022 16:40 |
Status: | Published |
Publisher: | American Chemical Society |
Refereed: | Yes |
Identification Number: | 10.1021/acs.chemmater.1c02096 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:178970 |