Hybrid crosslinking cellulose nanofibers-reinforced zwitterionic poly (ionic liquid) organohydrogel with high-stretchable, anti-freezing, anti-drying as strain sensor application

Conductive hydrogels (CHs) have demonstrated great potential application in wearable devices as a substitute for traditional rigid metal electrode sensors. However, the design of CHs with excellent mechanical stability for extreme environmental conditions remains a great challenge due to the high water content present in hydrogels. Herein, a novel anti-freezing and anti-drying zwitterionic poly (ionic liquid) organohydrogel was prepared via free-radical polymerization of acrylic acid (AA), 1-propyl-3-vinyl imidazole sulfonate (ZILs), cellulose nanofibers (CNFs) and ferric chloride (FeCl 3 ) in a glycerol/water mixture solvent. The synergistic interaction in the hybrid crosslinking, composed of physical/chemical crosslinking, endowed organohydrogel with desired mechanical properties, including stretchability (1032 %), self-recoverability (∼88 % recovery efficiency after 60 min), and excellent durability (500 cycles with 30 % deformation). Moreover, the organohydrogel exhibited satisfied conductivity (2.99 mS/cm), high strain-sensitive behavior (gauge factor (GF) up to 4.86), and significant sensing stability in a wide temperature range (−20–50 °C) due to the introduction of the binary solvent, the zwitterionic unit of ZILs, and Fe 3+ . Combined with the above advantages, a simple strain sensor was assembled, which offered remarkable real-time sensitivity in detecting human motions. This work provided new insights into the design of flexible sensors for applications in extreme environments.