Multimechanism Physical Cross-Linking Results in Tough and Self-Healing Hydrogels for Various Applications

Physical hydrogels are ideal candidates for functional materials and biomaterials, but their poor mechanical performance greatly restricts their applications. In this work, we develop a class of robust physical hydrogels based on multimechanism cross-linking. For this purpose, we use a hydrophobically associating (HA) hydrogel as the template, while simultaneously introducing graphene oxide (GO) and Laponite clay nanosheets into the gel system. The mutual stabilization between the two nanosheets assisted by surfactant within the HA system permits the addition of a relatively high concentration of nanosheets to enhance the hydrogel network. The resulting physical hydrogel is cross-linked by hydrophobically associating domains and two kinds of nanosheets and shows a series of desirable mechanical properties such as high strength and ductility, self-healing, and shape-memory abilities. These excellent mechanical properties, along with the versatility of both introduced nanosheets, enable various potential applications of these hydrogels, such as biosensors for the detection of body motion and reusable dye separators for wastewater treatment. Our results demonstrate a simple method to design tough physical hydrogels with various functions.