Rapid Polymerization of Anti-Freezing Hydrogels Using a Lignin Sulfonate–Zn²⁺ Self-Catalytic System for Strain and Temperature Sensors

Hydrogel electrolytes with antifreezing performance and excellent mechanical properties have become a research hotspot, but the general preparation process requires time and energy consumption, limiting the scope of applications. In this work, a simple, universal, and fast gelation based on a sodium lignin sulfonate macromolecule–zinc ion (LS-Zn 2+ ) self-catalytic system is developed. The catechol group of LS can coordinate with Zn 2+ to form complexes and accelerate the establishment of reversible oxidation–reduction, which can promote the rapid polymerization of vinyl monomers by generating various free radicals (OH• and 1 O 2 ). The gelation process does not require any additional energy and can be completed within 5 min by controlling the mass fraction of LS and the concentration of Zn 2+ or acids. The mechanical strength of the preferred hydrogel electrolyte can reach a tensile stress of 0.14 MPa under 1750% strain. The hydrogel electrolyte possesses an excellent conductivity of 3.67 mS cm –1 at extreme temperatures as low as −40 °C. The hydrogel electrolyte sensor can detect various parts of the human body in a wide temperature range with stable output resistance signals. This work provides a LS-Zn 2+ self-catalytic method for the rapid preparation of multifunctional hydrogels.