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Shape-Changing Tubular Hydrogels

Department of Chemical & Biomolecular Engineering, University of Maryland, College Park, MD 20742, USA
Author to whom correspondence should be addressed.
Received: 18 December 2017 / Revised: 15 February 2018 / Accepted: 17 February 2018 / Published: 22 February 2018
(This article belongs to the Special Issue Polyelectrolyte Gels)
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We describe the creation of hollow tubular hydrogels in which different zones along the length of the tube are composed of different gels. Our method to create these gels is adapted from a technique developed previously in our lab for creating solid hybrid hydrogels. The zones of our tubular gel are covalently bonded at the interfaces; as a result, these interfaces are highly robust. Consequently, the tube can be picked up, manipulated and stretched without suffering any damage. The hollow nature of these gels allows them to respond 2–30-fold faster to external stimuli compared to a solid gel of identical composition. We study the case where one zone of the hybrid tube is responsive to pH (due to the incorporation of an ionic monomer) while the other zones are not. Initially, the entire tube has the same diameter, but when pH is changed, the diameter of the pH-responsive zone alone increases (i.e., this zone bulges outward) while the other zones maintain their original diameter. The net result is a drastic change in the shape of the gel, and this can be reversed by reverting the pH to its original value. Similar localized changes in gel shape are shown for two other stimuli: temperature and solvent composition. Our study points the way for researchers to design three-dimensional soft objects that can reversibly change their shape in response to stimuli. View Full-Text
Keywords: hybrid hydrogels; stimuli-responsive polymers; smart materials hybrid hydrogels; stimuli-responsive polymers; smart materials

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

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Raghavan, S.R.; Fernandes, N.J.; Cipriano, B.H. Shape-Changing Tubular Hydrogels. Gels 2018, 4, 18.

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