High strength, self-healing, and anti-freezing polyurethane ionogel based on multiple hydrogen bonding for wearable strain sensor

Hydrogel-based electronic skin sensors often suffer from low mechanical properties, poor durability, and low temperature resistance. Herein, an ionogel was fabricated by casting the water-borne polyurethane (WPU) and 1-ethyl-3-methylimidazoliumdicyanamide (EMIM:DCA). The imidazolidinyl urea with multiple hydrogen bonds as chain extenders was introduced into WPU systems. Owing to the multiple hydrogen bonds, the ionogels exhibited good mechanical properties with a tensile stress of 1.45–12.09 MPa, a strain of 730%–860%, and good resilience. Moreover, the mechanical properties, conductivity, and sensing ability of the ionogels could be conveniently healed with the assistance of heat. EMIM:DCA endowed the ionogels with excellent ionic conductivity at room temperature (1.8–246 μS cm −1 ). In addition, due to the low vapor pressure of EMIM:DCA, the ionogel exhibited excellent anti-freezing property at −20°C. The ionogel can be assembled into a sensor to monitor the movements of human body with good responsiveness and stability.