Dynamic covalent bonds in self-healing, shape memory, and controllable stiffness hydrogels

Emerging technologies are increasingly reliant on materials that deliver multiple functionality. For example, hydrogels using dynamic covalent crosslinks have proven well-suited for the preparation of functional systems with properties including self-healing, shape memory, and stimuli-induced stiffness changes. These covalent bonds are capable of exchanging, dissociating or switching in response to various stimuli. In this review stimuli responsive dynamic covalent hydrogels are discussed on the basis of their chemistry and how the gels are increasingly used in novel applications. Challenges and potential future developments of dynamic covalent hydrogels are also discussed.