Mechanically tough, healable hydrogels synergistically reinforced by UV-responsive crosslinker and metal coordination interaction for wound healing application

Polymeric hydrogels prepared using organic crosslinking agents usually possess severely heterogeneous aggregation of crosslinking points because of their irregular free-radical polymerization, and the resulting mechanically weak and brittle properties greatly limit their potential applications. A straightforward strategy to improve their mechanical performance can be a combination of a uniform polymer network and a high healing capability, beneficial to restoring their structures and properties for practical applications. Herein, a facile and general strategy was reported to fabricate mechanically tough and highly efficient healable hydrogels composed of a chemically crosslinked network and metal-ligand coordination crosslinks, accompanied with highly stretchable, elastic and notch-insensitive properties. Combined with ultraviolet (UV)-responsive organic crosslinking agents, the resulting hydrogels made it possible to improve the dispersion of crosslinking points in the polymer network. The mechanical strength could be further enhanced through the introduction of metal ions (e.g., Ag+, Mn2+, Fe3+, Co2+, Ni2+, and Cu2+) in the formation of metal coordination interaction. Excitingly, in light of dynamic metal-ligand coordination as a healing motif, an optimal healing efficiency of 85% in 30 s could be achieved when exposed to microwave irradiation. Furthermore, hydrogels with excellent antibacterial activity and cell viability have been demonstrated, showing great potential as surgical dressings to accelerate wound closure.