Freezing-Tolerant Supramolecular Organohydrogel with High Toughness, Thermoplasticity, and Healable and Adhesive Properties.

Hydrogels based on supramolecular noncovalent interactions have attracted great research interest but are still limited by relatively low mechanical strength and performance deterioration at subzero temperatures because of the formation of ice crystallization. In this study, an antifreezing and mechanically strong gelatin supramolecular organohydrogel is prepared via a simple strategy of immersing a gelatin pre-hydrogel in the citrate (Cit) water/glycerol mixture solution. In the organohydrogel, a part of water molecules are replaced by glycerol, which inhibits the formation of ice crystallization even at extremely low temperature. In addition, the formation of noncovalent interactions such as the hydrophobic aggregation induced by the salting-out effect, ionic interactions between the -NH3+ of gelatin and Cit3- anions, and hydrogen bonding between gelatin chains and glycerol endows the organohydrogels with high mechanical strength and toughness. The supramolecular organohydrogel can maintain its mechanical flexibility even at -80 °C or be stored for a long time. Moreover, the nature of noncovalent interactions endows the organohydrogel with intriguing thermoplasticity, good healable ability, and excellent adhesive behavior at various substrate surfaces.