Starch-Based Ion-Conductive Organo-Hydrogels with Self-Healing, Anti-Freezing, and High Mechanical Properties toward Strain Sensors

Fully bio-based ion-conductive organo-hydrogels with multi-functionalities such as high mechanical properties, self-healing, anti-freezing, and non-drying capabilities are still extremely rare so far, and achieving it remains a great challenge. In this work, a starch/natural rubber composite hydrogel is first obtained by a simple one-pot method, and then an ion-conductive organo-hydrogel composed of starch, natural rubber, lithium chloride, and glycerol with adjustable mechanical properties (ultimate tensile stress of 0.15-2.33 MPa with a failure strain of 675-1367%, elastic modulus of 0.087-15.2 MPa) is fabricated by a solvent replacement strategy. The organo-hydrogels exhibit excellent fatigue resistance, elasticity, and good self-healing, anti-freezing, non-drying properties (with no obvious change after 10 days at ambient environment). The obtained hydrogels are successfully applied to monitor human movement with high durability (over 1000 cycles) and low hysteresis. In addition, the sensors exhibit high stability in a wide temperature range from -20 °C to 100 °C that endows it with a wide range of potential applications in flexible sensing and wearable devices.