Fig. 2: Electromechanical properties of OHGel and SHPU.

a Uniaxial tensile test results of OHGels with varying PE/GY ratio. Stretching speed, 60 mm min^-1. b Temperature dependence of OHGel’s ionic conductivity from −20 °C to 80 °C. c Photograph showing a SHPU substrate with OHGel loaded on top resisting the puncturing from a sharp tweezer. Scale bar, 5 mm. d Schematic illustration representing the hard-soft phase separation in SHPU (top); molecular structures of urethane hard domain (middle) and UPy-UPy dimer (bottom) that represent the hierarchical H-bonding in SHPU. e Stress-strain behaviors of pristine and self-healed SHPU samples after different healing durations. f Stress-strain cyclic behavior of SHPU under successive tensile loading up to 1000% strain. g Dielectric constant of SHPU, VHB 4905, and Sylgard 184 as a function of sampling frequency from 40 Hz to 10⁶ Hz. h Photographs recording the self-healing process of an OHGel-SHPU composite (left, scale bar, 10 mm); Schematic illustrations of the self-healing mechanisms in OHGel and SHPU (right). i Resistance change of the OHGel electrode upon bisection and reconnection. j Optical microscopic images recording the mechanical self-healing process of OHGel. Scale bar, 100 µm. k Resistance change of the OHGel electrode under uniaxial tensile strain after it was fully self-healed from damage.