Stretchable, anti-freezing and self-healing zwitterionic polyacrylate hydrogels for flexible wearable sensors

Traditional hydrogels are inevitably damaged during practical applications, resulting in a gradual deterioration of their functional efficacy. A primary strategy to address this issue involves developing hydrogels with inherent self-healing properties. In this study, we report the synthesis of self-healing polyacrylate hydrogels that integrate zwitterions, hydrophilic nano-silica and aluminum ions. Due to the synergistic effect of multiple hydrogen bonds, coordination bonds and electrostatic interactions, the tensile strength of the hydrogel is enhanced from 15.1 to 162.6 kPa. Moreover, the electrical resistance and tensile strength of the hydrogel can almost recover to its initial values after 20 min of healing at room temperature, exhibiting remarkable self-healing performance. Furthermore, the zwitterionic polyacrylate hydrogel serves as a wearable sensor with the capability of accurately response to the bending and stretching of human joints, exhibting a gauge factor of 1.87 under tensile strain ranging from 80% to 100%. Even after being freezed at −20 °C for 3 h, the zwitterionic polyacrylate hydrogel retains its exceptional writing performance. In conclusion, the hydrogels developed in this study demonstrate significant potential for wearable electronics applications.