Carboxymethyl chitosan-based tough hydrogels with low mechanical hysteresis and high conductivity as multifunctional sensors

Carboxymethyl chitosan (CA)/polyacrylamide (PAM) tough anti-freezing conductive (GCPC) hydrogels were fabricated via a simple one-pot method. The key innovation lies in strategic construction of interpenetrating network, reinforced by a synergistic interplay of hydrogen bonding, ionic coordination, and electrostatic interactions. Crucially, the CaCl 2 solution served a triple role: it dynamically cross-linked molecular chains to enhance mechanical toughness, acting as anti-freezing agent to suppress ice crystallization, enabling remarkable freezing resistance at ultra-low temperatures down to −50 °C, while simultaneously provides high conductivity for hydrogels as ionic electrolyte. These unique combinations endowed the GCPCs with remarkable strength (highest tensile strength of 1.24 MPa and highest compressive strength of 6.45 MPa), low hysteresis performance (6.02 % in tensile cycles and 22.09 % in compression cycles), excellent mechanical stability and durability (could withstand 1000 stretching and compression cycles without damage or relaxation) and high electrical conductivity (up to 7.20 S m −1 ). The GCPC could be assembled into a strain sensor and a temperature sensor, both of which delivered rapid, stable responses across extreme environments, highlighting their potential for multi-functional low-temperature wearable electronics and durable soft robotics. The present work is expected to provide a simple and efficient route for the preparation of multifunctional anti-freezing, tough and conductive hydrogels based on CA, and holds promise for a wide range of applications in soft sensor devices, suggesting new possibilities for technological progress within this domain.