Supramolecular hydrogels: Mechanical strengthening with dynamics

Supramolecular hydrogels display unique dynamic features such as self-healing and injectability which are endowed by their non-covalent crosslinking. These extraordinary dynamic properties enable them to be broadly applied in various fields, but also decrease their mechanical strength. This inherent contradiction between mechanical strength and dynamic features has posed great challenge to their practical applications. This article provides an overview of emerging techniques for mechanical strengthening of supramolecular hydrogels with preserved dynamic features. Inspired by the strong means slow principle of transient supramolecular networks, particular focus is placed on how the exchange kinetics of the supramolecular crosslinkers can be engineered to tune their mechanical strength. Some other effective strengthening strategies are also reviewed, which are usually combined to realize the coexistence of mechanical strength and dynamics. Meanwhile, we point out the future development of supramolecular hydrogels with unique mechanical properties and their potential challenges.