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-Zn2+) self-catalytic system is developed. The catechol group of LS can coordinate with Zn2+ 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 1O2). 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 Zn2+ 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-Zn2+ self-catalytic method for the rapid preparation of multifunctional hydrogels.