Effective negative swelling of hydrogel-solid composites

Effective negative swelling is a phenomenon that refers to the reduction of a solid volume after absorption of a solvent. Here, I focus on hydrogel solids and propose an alternative technique to achieve effective negative swelling. Particularly, I show that using homogeneous and isotropic hydrogel unit cells joined by rigid connections with impermeable inner cavities is enough to achieve this phenomenon. The key feature of this method is to use specific unit cells and decompose the problem in two steps; the first concerns the final shape of a unit cell after absorption of the solvent; the second consists in creating an array with these unit cells using rigid connections realizing what it may be called a metahydrogel. (C) 2018 Elsevier Ltd. All rights reserved.