An antifreeze polyzwitterionic eutectogel with high conductivity and sensitivity at arctic-like conditions for...

Traditional flexible conductive hydrogels use water as the dispersion medium, making them prone to freezing and cracking in low-temperature environments, rendering them unusable. Therefore, developing flexible materials that combine freeze resistance with high electrical conductivity to meet the demands of signal monitoring and energy storage in severe cold conditions is crucial for expanding the application boundaries of flexible wearable devices. This paper reports an effective strategy for preparing a flexible, freeze-resistant, and highly conductive polyzwitterionic eutectogel based on renewable nanocellulose. This strategy utilizes a three-dimensional cellulose network constructed via ionic crosslinking as the functional filler framework. Sulfonated betaine zwitterionic DMAPS ([2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide) is then in situ polymerized within this network to produce a dual-network composite eutectogel featuring both physical and chemical crosslinking interactions. The uniformly coexisting cellulose-Al³⁺ network and polyzwitterionic network provide the structural foundation for energy dissipation and ion migration. Consequently, eutectogels exhibits excellent tensile properties and high electrical conductivity (0.25-0.71 S·m^-1). The incorporation of deep eutectic solvents (DES) endows gels with exceptional antifreeze properties, maintaining excellent stability and outstanding ionic conductivity (0.24-0.65 S·m^-1) even under extreme conditions at -20 °C-virtually unchanged from its performance at room temperature (25 °C). Notably, the strain sensor based on eutectogels exhibits outstanding sensitivity performance both in low-temperature and ambient environments (GF = 2.70 at -20 °C and GF = 2.54 at 25 °C). This is attributed to the gel's ability to maintain its mechanical and electrical properties at low temperatures, demonstrating its potential for application under harsh conditions. Additionally, eutectogels have been successfully applied in pressure sensors and supercapacitors to monitor pressure signals and store energy. Overall, this study has developed a promising strategy for preparing functional, freeze-resistant green composite sensors for engineering applications.