PEG-free pH-Responsive Thermogels Containing Amphiphilic Polycationic Polyethylenimine Copolymers

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PEG-free pH-Responsive Thermogels Containing Amphiphilic Polycationic Polyethylenimine Copolymers
Title:
PEG-free pH-Responsive Thermogels Containing Amphiphilic Polycationic Polyethylenimine Copolymers
Journal Title:
Macromolecules
Keywords:
Publication Date:
22 November 2023
Citation:
Lin, Q., Lim, C. C., Owh, C., Wong, J. H. M., Ow, V., Sim, B., Boo, Y. J., Yew, M. P. Y., Leow, Y. H., Guo, L., Lim, J. Y. C., & Loh, X. J. (2023). PEG-free pH-Responsive Thermogels Containing Amphiphilic Polycationic Polyethylenimine Copolymers. Macromolecules, 56(23), 9368–9378. https://doi.org/10.1021/acs.macromol.3c01600
Abstract:
Thermogels are a class of supramolecular hydrogels that exhibit reversible sol–gel phase transitions upon temperature changes and whose unique properties are critically dependent on their constituent polymers’ hydrophilic–hydrophobic balance. To date, the overwhelming majority of thermogelling polymers employ poly(ethylene glycol) (PEG) as the archetypical hydrophilic segment, with the usage of other hydrophilic polymers such as polyethylenimine (PEI) virtually unknown. Herein, we expand the possibilities in thermogel polymer design through a family of PEG-free amphiphilic polymers comprising only PEI and poly(propylene glycol) (PPG) as the sole hydrophilic and hydrophobic segments, respectively, that can spontaneously self-assemble into micelles and supramolecular gel matrices. By leveraging well-established amine chemistry, we demonstrate easy and mild postsynthetic modification of these PEI-PPG copolymers by quaternarization with benzyl groups, allowing a convenient means to modulate the resulting thermogel properties. In addition, through systematic variation of the copolymers’ hydrophobic–hydrophilic balance, we show that the critical gelation concentrations, gelation temperatures, and gel viscoelastic properties can be tuned. Finally, on top of temperature responsiveness, the PEI segment also afforded pH-responsiveness by protonating the basic amine groups under acidic conditions, offering additional opportunities for altering thermogel viscoelasticity through ph adjustment. The convenience of postsynthetic functionalization, new material properties, and dual stimuli-responsiveness of these polycationic PEI-PPG thermogels can potentially offer a vast material design space for many unique applications.
License type:
Publisher Copyright
Funding Info:
This research / project is supported by the National Research Foundation, Singapore, and Agency for Science, Technology and Research (A*STAR) - IAF-PP - Ocular Biomaterials for Vitreoretinal Therapeutic Applications
Grant Reference no. : H20c6a0033

This research / project is supported by the National Research Foundation, Singapore - NRF Investigatorship - Thermogels for Therapeutic Applications
Grant Reference no. : NRF-NRFI07-2021-0003

This research is supported by core funding from: SERC (A*STAR Central Research Fund)
Grant Reference no. : SC25/21-808816
Description:
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 10.1021/acs.macromol.3c01600.
ISSN:
0024-9297
1520-5835
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