Dual-ionic hydrogels with ultralong anti-dehydration lifespan and superior anti-icing performance

Water-rich hydrogels find a wide range of promising applications due to their combined solid/liquid-like properties. However, hydrogels often exhibit a short lifespan and suffer from functional failure due to water depletion via rapid evaporation and icing/freezing under low temperatures. To tackle these challenges, here we developed a Ca2+ and hydrophilic bonded -SO3− group-based dual-ionic hydrogel (DIH) which possesses an ultralong anti-dehydration lifespan and outstanding anti-icing properties. The as-developed DIH can keep wet and flexible as its initial state for longer than 8 months in practical room environment (15–35 °C, relative humidity of 30–90%), and show low ice adhesion of 2.3 kPa and durably frost-free property at -10.0 °C as well as anti-freezing property down to -49.0 °C. According to the molecular dynamic simulations and experimental results, the superior anti-dehydration performances are due to the low-diffusion and high absorption capacity and self-replenishment of water via the dual-ionic strategy; the sufficient anti-icing Ca2+ result in the extremely low melting point and anti-icing properties of the DIH. This design sheds new light on developing next-generation durable hydrogels with applications in soft materials and functional surfaces under harsh conditions of both low humidity and low temperatures.