Supramolecular Zwitterionic Hydrogels for Information Encryption, Soft Electronics and Energy Storage at Icy Temperature

Abstract Zwitterionic hydrogels have attracted intensive attentions for their exceptional hydration and anti‐fouling properties, while the exploration for rational structural designs to achieve multi‐function and superior anti‐freezing capability remains an ongoing mission. Herein, a new multi‐functional zwitterionic monomer (ACHPES) is designed and developed from which novel zwitterionic hydrogels are fabricated. The pyridinium‐sulfonate zwitterionic motif endows the hydrogel with discoloration in both visible light and fluorescence in response to pH stimulus, enabling unique multi‐channel information encryption and highly sensitive Cu²⁺ detection with a detection threshold of 0.64 ppm. The design of carbamate group fulfils hydrogel high bonding capacity with water, leading to superior anti‐freezing capability. As such, the hydrogels exhibit an extremely low water freezing point of −47.3 °C and a high breaking elongation of ≈500% at −20 °C. The outstanding anti‐freezing capability enables hydrogel sensors and electrolytes an excellent operational performance at freezing temperatures. This innovative design strategy offers a new avenue for functionalization and application of zwitterionic hydrogels at icy temperature.