Hybridized Hydrogen Bonding Strategy to Construct Antifreezing Hydrogels for Wearable Sensors

Hydrogels are widely used across various fields, creating a demand for materials capable of withstanding freezing conditions. Most existing antifreezing hydrogels rely on small-molecule additives or are organogels, which frequently encounter environmental concerns due to potential toxicity and exhibit poor long-term stability in harsh conditions. In this study, we propose a hybridized hydrogen bonding strategy to develop antifreezing hydrogels without the need for small-molecule additives. The freezing resistance is achieved through interactions between the hydrogel's polar functional groups (the -COOH group of poly(acrylic acid), the -CO- group of polyvinylpyrrolidone, and the -OH group of phytic acid) and water molecules, which modify the distribution of hydrogen bonds within the system. These hydrogels demonstrate excellent mechanical resilience (92%) and conductivity, both of which are maintained at subzero temperatures. Additionally, flexible sensors made from these hydrogels exhibit reliable signal stability in low-temperature environments. This work presents an effective strategy for improving the freezing resistance of hydrogels, advancing our understanding of antifreezing mechanisms, and providing practical insights for future applications, particularly in wearable sensor technologies.