One-Step in Situ Synthesis of Tough and Highly Conductive Ionohydrogels with Water-Retentive and Antifreezing Properties

Flexible and conductive gels are promising materials as intelligent and wearable electronics. Herein, through a facile one-step in situ free-radical polymerization, tough VSNPs-PAA-Zr⁴⁺ ionohydrogels with integrated multiple functionalities are prepared, which are dually cross-linked by multivalent vinyl-functionalized silica nanoparticles (VSNPs) and metal coordination between Zr⁴⁺ and the carboxyl groups in PAA chains. The incorporation of Zr⁴⁺ with stable valency during polymerization enables the direct formation of a large number of metal coordination cross-links for adequate energy dissipation, overcoming the inhibition of unstable metal ions on the polymerization process. Meanwhile, VSNPs serve as multivalent cross-linkers and effective stress transfer centers. The obtained VSNPs-PAA-Zr⁴⁺ ionohydrogels show high toughness of up to 25 MJ m^-3 with a high tensile strength of 3010 kPa and a large elongation at break of 1360%, along with reliable adhesive performance. Attributed to use of an IL/water binary solvent, the ionohydrogels possess excellent water-retentive and antifreezing abilities. Moreover, the existence of large quantities of mobile ions endows the VSNPs-PAA-Zr⁴⁺ ionohydrogels with a superior conductivity of 4.77 S m^-1 and a high strain sensitivity with a gauge factor (GF) of 9.04, which are promising materials as intelligent and wearable strain sensors.