Solvent-Triggered Self-Folding of Hydrogel Sheets

Intense investigations have been attracted to the development of materials which can reconfigure into 3D structures in response to external stimuli. Herein we report on the design and self-folding behaviors of hydrogels composed of poly(ethylene glycol) methyl ether methacrylate (OEGMA) and 2-(2-methoxyethoxy) ethyl methacrylate (MEO\begin{document}$_{2}$\end{document}MA). Upon immersion into a variety of solvents at room temperature, the resulting P(MEO\begin{document}$_{2}$\end{document}MA-co-OEGMA) hydrogel sheets self-fold into 3D morphologies, and the observed transformation in shape is reversible. We further show that composition of the gel, gaseous environment, and preparation procedure play important roles in the self-folding behavior of the resulting hydrogels. This work provides a facile approach for fabricating self-folding hydrogels.