Ionic conductive hydrogels with long-lasting antifreezing, water retention and self-regeneration abilities

Abstract

Conductive hydrogels have emerged as promising materials for flexible electronics due to their integrated conductivity and mechanical flexibility. However, they turn to rigid and poorly conductive at subzero temperature because of inevitable water freezing. Besides, they also suffer from poor water retention ability and cannot self-regenerate to their original state after dehydration. Herein, a novel ionic conductive poly (sulfobetaine-co-acrylic acid) hydrogel possessing antifreezing, water retention and self-regeneration abilities was developed by introducing a highly hydratable salt-lithium chloride. The hydrogel could endure ultralow temperature (−80 ℃) over 30 days without freezing and retain ~100% of its initial water content after storage at ambient temperature (25 ℃, 54% humidity) for 1 week. Moreover, after vacuum drying, the dehydrated hydrogel could self-regenerate by spontaneously harvesting water molecules from surrounding environments even at −40 ℃, which had not been achieved by previously reported conductive hydrogels. These properties enabled the hydrogel with a wide working temperature range and extended lifespan for the development of more advanced and sustainable flexible electronics.