Natural UCST hydrogel with long-term stability, recyclability, thermoplasticity, frost resistance and adhesive properties

Thermosensitive hydrogels have received great research interest, but the elaborate experimental design, inferior mechanical and anti-freeze properties have limited the practical application of thermosensitive hydrogels. For address these challenges, here, polyol (glycerol, xylitol, and sorbitol) and deionized water were selected as mixed solvents to fabricate multifunctional natural gelatin UCST hydrogels by simple physical blending. XRD and FT-IR indicate that the polyol assists the gelatin molecular chain to form short-range β-sheets without affecting the triple helix structure. The short-range β-sheets acts as the physical cross-linking point, which leads to a denser three-dimensional network of the hydrogel. The results indicate that the phase transition temperature and mechanical properties of UCST hydrogels can be modulated by simply changing the amount of polyol in the solvent mixture. In addition, the polyol forms extensive hydrogen bonds with water, which gives the hydrogel excellent freeze resistance, anti-drying and adhesive properties. In this paper, natural UCST gelatin hydrogels with long-term stability, recyclability, thermoplasticity, anti-freeze and adhesive properties were prepared by a simple scheme, and the facile process and cheap cost lays the foundation for the application of UCST hydrogels in drug delivery, skincare products and wearable devices.