Graphene Oxide Encapsulating Liquid Metal to Toughen Hydrogel

Abstract Stretchable and tough hydrogels are highly required for various flexible devices. Liquid metal (LM) emerges as an attractive applicant in preparing functional hydrogels due to its unique features. However, the high fluidity of LM and incompatibility between LM and polymer matrix make it hard to fabricate tough hydrogels. Herein, inspired by the function of ligaments in biological structure, graphene oxide (GO) nanosheets are introduced to encapsulate LM droplets. GO nanosheets form strong interaction with both LM and polymer matrix to create a stable shell that prevents LM droplet from fracture and exudation to polymer network. The flexible LM/GO core–shell microstructure avoids phase separation and produces a tough hydrogel with stress of high up to 303 kPa at 1240% elongation. It also shows notch insensitivity and strong adhesion to various surfaces. This study opens the possibility of using LM in stretchable and tough hydrogels.