Ultrastretchable,\nTough, Antifreezing, and Conductive Cellulose Hydrogel for Wearable\nStrain Sensor

Abstract

Conductive hydrogels have shown great\npotential in the field of flexible strain sensors. However, their\napplication is greatly limited due to the low conductivity and poor\nmechanical properties at subzero temperatures. Herein, an ultrastretchable,\ntough, antifreezing, and conductive cellulose hydrogel was fabricated\nby grafting acrylonitrile and acrylamide copolymers onto the cellulose\nchains in the presence of zinc chloride using ceric ammonium nitrate\nas the initiator. The resulting hydrogel exhibited ultrastretchability\n(1730%), excellent tensile strength (160 kPa), high elasticity (90%),\ngood toughness (1074.7 kJ/m³), and fatigue resistance property\ndue to the existence of dipole–dipole and multiple hydrogen-bonding\ninteractions on the hydrogel network. In addition, the introduced\nzinc chloride endowed the cellulose-based hydrogel with remarkable\nelectric conductivity (1.54 S/m) and excellent antifreezing performance\n(−33 °C). Finally, the hydrogel showed high sensitivity\nand stability to monitor human activities. In summary, this work presented\na facile strategy to construct conductive hydrogel with excellent\nantifreezing and mechanical properties simultaneously, which showed\ngreat potential for wearable strain sensors.