No abstract

Chitosan-based single network hydrogels with imine bonds have excellent self-healing capability, while poor mechanical properties limit their applications. Here, chitosan-polyacrylamide-based double network hydrogels were prepared via in situ free-radical polymerization of acrylamide in the presence of N-carboxyethyl chitosan (CEC) and dibenzaldehyde-terminated telechelic poly(ethylene glycol), which had excellent mechanical properties, self-healing, and dual-responsive shape memory abilities. The maximum tensile strength and elongation at break could reach 460 kPa and 4600%, respectively. Meanwhile, owing to the reversibility of imine bonds, elongation and strength at break of hydrogels could heal by 84.2 and 93.2% under alkali stimulation at 35 C, respectively. Furthermore, the hydrogels also had good shape memory abilities for pH-stimuli responsiveness of the imine bonds and metal ions stimuli responsiveness of CEC. The prepared chitosan-based functional hydrogels have great potential application prospects in tissue scaffolds, actuators, and wearable devices.

The currently reported self-healing hydrogels have problems of low mechanical strength, single performance, and poor self-healing efficiency, which greatly limit their applications. Here, through adding N-carboxyethyl chitosan to acrylic-Fe 3+ system, the self-healing physically crosslinked hydrogels were prepared via in situ free radical polymerization, which have excellent self-healing ability and mechanical properties. The maximum tensile strength and elongation at break of the hydrogels can reach up to 280 KPa and 1900%, respectively. Owing to the reversibility of coordination, self-healing efficiency of the hydrogels can reach 98% in 2.5 h. Moreover, the hydrogels also have good conductivity due to the migration of Fe 3+ . This strategy can broaden the applications of chitosan-based self-healing hydrogels.Since the metal coordination has multiple coordination points, it can form hydrogels with high strength and self-healing ability. Metal ions, like Fe 3+ , Zn 2+ , Cu 2+ , can form strong coordination with some groups, such as OH, COOH, NH 2. 32-34 The ionicAdditional Supporting Information may be found in the online version of this article.