Self-adhesive, freezing-tolerant conductive organohydrogels with variable transparency and rapid repairing for multi-functional sensor

Organohydrogels have garnered considerable attention in the field of flexible sensors, largely because of their flexibility, durability, and multifunctionality. However, conventional organohydrogels demonstrate inadequate conductivity, necessitate substantial preparation time and energy, are challenging to repair following damage, exhibit immutable transparency, and are inherently unstable in extreme environments, which significantly restricts their practical application. Herein, a conventional synergetic self-catalytic system based on catechol molecules and metal ions was innovated for the rapid fabrication of conductive polyacrylic acid (PAA) organohydrogels in H 2 O/ethylene glycol (EG)/LiCl solvent. The dual self-catalytic system comprises ferric ions (Fe 3+ ) and cellulose nanofibers (CNF) coated with tannic acid (TA@CNF), which form stable redox pairs to activate ammonium persulfate (APS), thereby initiating the polymerization of monomers rapidly and effectively. Compared with other gel prepared by catechol metal ion autocatalysis system, the organohydrogel prepared by us has unique advantages, including: (1) Modifying the pH value of the TA-coated CNF enables a change in the transparency of the organogel and enhances its mechanical properties. (2) The color of the organohydrogel can be modified by adjusting the equilibrium of the redox system by APS. (3) The organohydrogel has the ability to rapid repairing (50 s). Moreover, the organohydrogel exhibits considerable tensile strength, satisfactory self-adhesion (44.2 ± 4.3 kPa), excellent conductivity (1.79 ± 0.035 S/m) and extreme environmental applicability (−60 °C to 45 °C). The organohydrogel displays excellent conductivity, sensitive response to tensile deformation, changeable color, rapid repairing and excellent mechanical properties. Thus, it can be applied to human movement monitoring, information encryption and intelligent control.