Preparation and properties of acrylate/polyvinyl alcohol self-healing hydrogels based on hydrogen bonds and coordination bonds

Despite the widespread attention garnered by self-healing hydrogels in various fields, achieving a balance between high mechanical strength and self-healing capability remains a challenge. Particularly, the addition of fillers in the fabrication of spray-coated waterproof materials hinders the movement of molecular chains. Simultaneously, the self-repair of metal ions is hindered by issues such as a prolonged required time and low repair rate. Therefore, we introduce a polyvinyl alcohol (PVA) solution subjected to freeze-thaw cycles into the acrylic acid magnesium/calcium hydrogel system, creating a self-healing hydrogel with an interpenetrating polymer network (IPN). Due to the abundance of hydroxyl groups on the PVA molecular chains, during the freezing process, some PVA chains form microcrystals that do not dissolve upon thawing at room temperature. These microcrystals act as cross-linking points, connecting PVA chains into a 3D network. Consequently, the hydrogel, under the dual effects of hydrogen bonds and coordination bonds, exhibits excellent mechanical properties and the ability to self-heal at room temperature. Furthermore, by adjusting the concentration of the PVA solution, the mechanical properties and healing ability of the hydrogel can be tailored to meet various construction requirements.