One-Step Fabrication of Robust, Nondrying, Elastic Gelatin Hydrogels with Self-Healing and Recycling Capabilities

Gelatin hydrogels, a kind of ideal biobased material with excellent biodegradability and biocompatibility, are weak and easy to dehydrate in an ambient environment, which greatly hinders their practical application. In this study, we have developed a simple strategy to fabricate robust, nondrying, elastic gelatin hydrogels through introducing choline chloride (ChCl) in hydrogel networks. Benefiting from the hydrated ions of ChCl, the water content can be simply controlled by adjusting the amount of ChCl; as a result, the mechanical strength of the gelatin hydrogel can be regulated from 9.5 to 0.6 MPa through tuning the water content as well as the tensile strain from 229 to 690%. Most importantly, the water content of the hydrogels can be kept unchanged for at least 30 days, which resolves the prerequisite for the long-time use of the hydrogels. Besides, the gelatin hydrogels exhibit good self-healing, conductive, antifreezing, and recyclable properties. Combining with the above excellent performance, the proposed hydrogels are successfully applied as flexible sensors to monitor human movement. This study demonstrates a novel strategy for the design of gelatin hydrogels with high performance.