Dynamic covalent polymer hydrogels and organogels crosslinked through acylhydrazone bonds: synthesis, characterization and applications

Abstract We review recent literature on the rapidly expanding field of dynamic covalent polymer networks (DCPNs) crosslinked with acylhydrazone bonds, classified according to their structural perfection: randomly crosslinked and model DCPNs. The dynamic covalent acylhydrazone bond is greatly sensitive to environmental conditions, pH in particular, and is characterized by great stability under neutral and mildly alkaline conditions, and instability under acidic conditions. The dynamic nature of this bond endows DCPNs crosslinked with acylhydrazone bonds with self‐healing ability, reversibility and injectability. The last property enables the in vivo site‐specific delivery of drugs, biomolecules or cells that have been loaded into DCPN hydrogels. © 2018 Society of Chemical Industry