An organohydrogel consists of a crosslinked polymer network swollen by a water-organic solvent mixture, or by an organic liquid alone, rather than by water [1]. The organic component lowers the freezing point and the vapour pressure of the liquid phase, so the network stays soft below zero degrees Celsius and retains its mass in open air for longer than a conventional hydrogel [2]. Solvent composition also changes the solubility of the network: a poor solvent contracts the chains and raises modulus, whereas a good solvent swells them and lowers it [1]. Where the two liquids differ in affinity for the polymer, they separate into domains, and that heterogeneity raises toughness because a crack is deflected at the boundary [3]. Ionic conductivity survives in the organic-rich phase, which is why the same network can serve at low temperature [2].
Hydrogels: synthesis, properties, applications·Molecular Medicine·Biochemistry, Genetics and Molecular Biology·Life Sciences