Self-healing, stretchable, and freezing-resistant hydroxypropyl starch-based double-network hydrogels

[Display omitted] •Double-network hydrogels were prepared by hydroxypropyl starch and sodium alginate.•The hydrogels formed by hydrogen bonding and metal coordination crosslinking.•The hydrogels were stretchable, compressible, and self-healing.•The hydrogels prepared by water and glycerol can maintained gel properties at -30 °C. Starch hydrogel is a biocompatible and biodegradable material. However, due to its poor mechanical properties and fragility, starch hydrogel has limited applications in the food and medicine industries. In this work, we prepared stretchable, compressible, and self-healing double-network (DN) hydrogels using hydroxypropyl starch (HPS) and sodium alginate (SA). By adjusting the amount of sodium alginate added, the DN hydrogels achieved adjustable mechanical properties. The storage modulus of the DN hydrogels with 1% SA increased by nearly 80 times compared with that of pure HPS hydrogels. When prepared in a water/glycerol binary mixed solvent, the DN hydrogels can maintain their gel properties at -30 ºC. These environmentally friendly and biocompatible hydrogels have broad application prospects in the fields of agriculture, food, and medicine.