Salt-welding strategy for the design of repairable impact-resistant and wear-resistant hydrogels

Self-healing hydrogels can autonomously repair damage, enhancing their performance stability and broadening their applications as soft devices. Although the incorporation of dynamic interactions enhances self-healing capabilities, it simultaneously weakens the hydrogels' strength. External stimuli such as heating, while accelerating the healing process, may also lead to dehydration. Developing a stable repair strategy that combines rapid healing and high mechanical strength is challenging. Here, we introduce "salt-welding" for high-strength hydrogels with rapid room temperature self-healing. This is achieved through dynamic borate ester bonds in a salt-responsive poly(methacrylamide) hydrogel. The process involves "salt-fusion" to convert fractures into a viscous liquid for swift healing, followed by "salt-concretion" to toughen the hydrogel. The hydrogels achieve a posthealing strength of 23 megapascals in 95 minutes at room temperature, with near 100% healing efficiency. Leveraging their tunable mechanical strength and rapid healing rate, the hydrogel can be tailored for applications as a reparable wear-resistant material and damping device.