Dual-cross-linked dynamic hydrogels with cucurbituril and imine linkages
The strategy of dual cross-linking was investigated in enhancing the performance of dynamic hydrogels. To this end, phenylalanine modified ε-polylysine was synthesized and employed as the polymer backbone of the hydrogels. The phenylalanine moieties and amine groups of the polymer could be cross-linked with cucurbituril (CB) and dialdehyde cross-linker, respectively. Single CB linkage with fast dynamics led to the increase in viscosity of the polymer solution, and single imine linkage with slow dynamics led to the formation of weak and brittle hydrogels. However, combine the two linkages together to form the dual-cross-linked hydrogel and the performance of the hydrogel could be well enhanced. Compared with the single imine cross-linked hydrogel, the dual-cross-linked hydrogel demonstrated higher mechanical strength, better extensibility and faster self-healing rate. It is anticipated that this line of research would provide a useful method to enhance the performance of dynamic hydrogels.