Water and stress tension dual-response antifreeze conductive hydrogel with optically tunable behavior and sensing applications

Conductive hydrogels have been widely used in flexible electronics, soft robotics, and health monitoring due to their high stretchability, tunable conductivity, and biocompatibility. However, the weak mechanical properties and low environmental resistance of conductive hydrogels limit their applications. Herein, based on multiple hydrogen bonds and ionic crosslinking strategies, an ionic conductive AlCl₃/poly(acrylamide-co-methyl methacrylate) [AlCl₃/P(AM-co-MMA)] hydrogel containing DMSO/H₂O binary solvent system was prepared. The obtained hydrogel not only possessed a tensile stress/strain of 1.74 MPa/803% but also showed excellent environmental resistance, remaining flexible at −40 °C. In addition, benefiting from the in-situ phase separation and recovery of MMA hydrophobic chains in water and DMSO/H₂O solution, the hydrogel could realize the optical transition from milky white to transparent, which could be used for information writing and erasure encryption. Furthermore, a flexible sensor based on the hydrogel was fabricated, which exhibited a sensitivity of 0.41, a detection range of 1–400%, and a response time of 300 ms, respectively, capable of being used for human motion detection. Overall, this work provided a new idea for the integrated application of conductive hydrogels with multiple outstanding functions.

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