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

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.