Cellulose/Sodium Polyacrylate Interpenetrating Network Hydrogel with Intrinsic Anti-Freezing Property

Generally, small molecule alcohols and concentrated electrolyte ions can be introduced into the medium of hydrogels as anti-freezing agents to achieve significant anti-freezing properties. However, due to the exchange effect with the external environment, the anti-freezing agents may leak or change in composition causing contamination and unstable material performance during use. Here, cellulose and sodium polyacrylate (PAAS) were used to construct interpenetrating network hydrogels, with cellulose comprising up to 63% of the system. Sodium ions and carboxylic acid groups ionized from the polyacrylate network restricting the formation of water clusters through strong hydration and significantly reduced the ice crystal formation temperature. The rigid cellulose networks provided mechanical strength for the hydrogels. The new interpenetrating network hydrogels exhibited a low anti-freezing temperature (lowest at -56.12 °C), a high water content (over 82.5 wt%), and considerable toughness (up to 2.53 MJ m^-3). The intrinsic anti-freezing hydrogel constructed in this work provides a new reference strategy for expanding the practicability of anti-freezing hydrogels.