Autonomous Volume Transitions of a Polybase Triblock Copolymer Gel in a Chemically Driven pH-Oscillator

Paul D. Topham, Jonathan R. Howse, Colin J. Crook, Anthony J. Gleeson, Wim Bras, Steven P. Armes, Richard A. L. Jones, Anthony J. Ryan

Research output: Contribution to journalArticlepeer-review

Abstract

A pH‐responsive ABA triblock copolymer, comprising poly(methyl methacrylate)‐block‐poly(2‐(diethylamino)ethyl methacrylate)‐block‐poly(methyl methacrylate) [PMMA‐b‐PDEA‐b‐PMMA], has been cast into thin films with a well‐defined microstructure. Small Angle X‐ray Scattering (SAXS) and Atomic Force Microscopy (AFM) studies confirm that this copolymer forms a hydrogel consisting of PMMA spheres embedded within a polybase PDEA matrix, with the PMMA domains acting as physical cross‐links. The hydrogel has a pH‐reversible coil‐globule transition at around pH 4.5. This responsive physical property was exploited by immersing a sample of copolymer hydrogel in an aqueous solution containing a cyclic pH‐oscillating reaction, whereby the pH was continuously oscillated above and below the transition pH so as to induce autonomous volume transitions. The changes in microscopic and macroscopic length scales correlate closely during (de)swelling cycles, with affine behaviour occurring over five orders of magnitude.
Original languageEnglish
Pages (from-to)95-104
JournalMacromolecular Symposia
Volume256
Issue number1
DOIs
Publication statusPublished - 25 Sep 2007

Bibliographical note

This is the peer reviewed version of the following article: Topham, P. D., Howse, J. R., Crook, C. J., Gleeson, A. J., Bras, W. , Armes, S. P., Jones, R. A. and Ryan, A. J. (2007), Autonomous Volume Transitions of a Polybase Triblock Copolymer Gel in a Chemically Driven pH‐Oscillator. Macromol. Symp., 256: 95-104, which has been published in final form at https://doi.org/10.1002/masy.200751011.  This article may be used for non-commercial purposes in accordance With Wiley Terms and Conditions for self-archiving.

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