3D Printable Organohydrogel with Long-Lasting Moisture and Extreme-Temperature Tolerance for Flexible Electronics.

Hydrogels with high electrical conductivity and mechanical stretchability are promising materials for flexible electronics. However, traditional hydrogels are applied in short-term usage at room temperature or low temperature due to their poor water-retention ability and freezing-tolerance property. Here, a dually cross-linked glycerol-organohydrogel (GL-organohydrogel) based on GL and acrylic acid was synthesized in a GL-water binary solvent. Fe 3+ ions working as an electrolyte were added to improve the conductivity of the organohydrogel and form coordination interactions between Fe 3+ ions and carboxyl groups of acrylic acid. The strong hydrogen bonding between GL and water molecules firmly lock water in the organohydrogel network, thereby endowing the GL-organohydrogel with the antifreezing property, long-term stability, and moisture lock-in capability. Our organohydrogel could endure extremely low temperature (-80 °C) over 30 days without freezing and retain its water content (almost 100% of its initial state) after being stored at room temperature (25 °C, 54% humidity) for 30 days. It also demonstrated desired stretchable properties, conductivity, three-dimensional (3D) printability, and self-healing ability. A wearable data glove was constructed by using the GL-organohydrogel and digital light processing technology. This work opens a new avenue for developing hydrogels with long-term stability, moisture lock-in capability, and extreme-temperature tolerance for stretchable electronics.