Development of an Ultrastretchable Double-Network Hydrogel for Flexible Strain Sensors

The weak mechanical properties of hydrogels due to the inefficient dissipation energy in intrinsic structures limit their practical applications. Here, a double-network (DN) hydrogel has been developed by integrating an ionically cross-linked agar network, covalently acrylic acid (AAC) and dynamic reversible coordination between AAC chains Fe3+ ions. proposed model reveals mechanisms improved performances DN agar/AAC-Fe3+ hydrogel. hydrogen-bond double helices ionic-coordination interactions AAC-Fe3+ can be temporarily sacrificed during large deformation readily dissipate energy, whereas regenerated after stress relief, which greatly increases material toughness. demonstrates remarkable stretchability with break strain up 3174.3%, high sensitivity gauge factor being 0.83 under 1000%, good 3D printability, making desirable candidate for fabricating flexible sensors, electronic skin, soft robots.