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Issue 18, 2011
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Oscillatory dynamics induced in a responsive gel by a non-oscillatory chemical reaction: experimental evidence

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Abstract

We provide experimental confirmation of the numerical simulations that predicted spontaneous chemo-mechanical oscillations induced by the size-changes of a pH-responsive hydrogel immersed in the proton-autoactivated bromate-sulphite (BS) reaction. The gel swells and shrinks in a constant and uniform non-equilibrium environment, with no external stimuli. Oscillations result neither from a kinetic feedback in the reaction mechanism nor from long-range activation diffusion instability. The dynamics clearly arises from the feedback that the size responsiveness of the hydrogel exerts on the relative stability of two different pH gradient profiles inside the gel. No oscillations occur without - or with insufficient - size-change of the gel. This is opposed to systems where the mechanical changes are merely slaved to the reaction kinetics. The present progress was obtained by considerably enhancing the swelling-deswelling ratio of the pH-responsive gel by tuning its hydrophobicity. We succeeded in producing more than a dozen of chemomechanical oscillations for over 48 h. We also demonstrate that the system is capable of working under mechanical stress, repeatedly lifting an object weighing 10 times the weight of the swollen gel.

Graphical abstract: Oscillatory dynamics induced in a responsive gel by a non-oscillatory chemical reaction: experimental evidence

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Publication details

The article was received on 11 Feb 2011, accepted on 24 May 2011 and first published on 19 Jul 2011


Article type: Paper
DOI: 10.1039/C1SM05226H
Citation: Soft Matter, 2011,7, 8462-8472
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    Oscillatory dynamics induced in a responsive gel by a non-oscillatory chemical reaction: experimental evidence

    J. Horváth, I. Szalai, J. Boissonade and P. De Kepper, Soft Matter, 2011, 7, 8462
    DOI: 10.1039/C1SM05226H

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