PVA/Agar Interpenetrating Network Hydrogel with Fast Healing, High Strength, Antifreeze, and Water Retention

Traditional self-healing hydrogels have great application prospects in biological engineering because of their extremely high water content, but their durability cannot be easily guaranteed. Therefore, developing a rapid self-healing hydrogel with long-lasting water retention capacity is still a significant challenge. A high-strength and fast self-healing hydrogel with an interpenetrating double network based on polyvinyl alcohol/agar-ethylene glycol (PVA/agar-EG) is proposed. Polyvinyl alcohol (PVA) and agar are designed for the construction of the interpenetrating network. Furthermore, the introduction of a borate-bonding dynamic action mode affords the hydrogel with extraordinary mechanical strength and rapid self-healing. The addition of EG as a traveling solvent enables the sample to retain water and prevents freezing in harsh environments, including at high temperatures of 80 °C and extremely low temperatures of −40 °C. Additionally, owing to the intelligent remolding ability of the PVA/agar-EG hydrogel, the material can be recycled to prolong the service life of the hydrogel. Overall, the PVA/agar-EG hydrogel developed in this study can provide a new general strategy for the development of intelligent self-healing devices, and hydrogels can be applied in complex environmental engineering.