Cellulose nanofiber-reinforced chitosan conductive hydrogel tailored by double-network strategy for stretchable...

Benefiting from the unique properties such as flexibility, bio-tissue-like mechanical compliance and adjustable conductivity, conductive hydrogels have demonstrated great application prospects in the field of wearable sensors. However, synthetic polymer-based conductive hydrogels are poorly biocompatible, and their overuse can exacerbate resource depletion. Herein, a biobased conductive hydrogel with double-network structure was prepared for stretchable strain sensors by synergistic interaction of carboxymethyl chitosan, carboxylated cellulose nanofibers, calcium chloride and ionic liquid. Owing to the reinforcing effect by nanofibers and the construction of double-network, the conductive hydrogel showed good mechanical properties with elongation at break of 406.7 % and tensile strength of 248.9 kPa, and the corresponding Young's modulus and toughness were 69.2 kPa and 527.6 kJ/m³, respectively. Moreover, the conductive hydrogel exhibited excellent conductivity and freezing resistance, its ionic conductivity and freezing point reached 1.073 mS/cm and -12.32 °C, respectively. Meanwhile, the conductive hydrogel showed remarkable cell compatibility, skin-friendliness and biodegradability. In addition, the conductive hydrogel-based stretchable strain sensor possessed good comprehensive sensing performance and was able to accurately recognize joint flexion and subtle changes of human body. The strategy to prepare biobased and high-performance conductive hydrogel in this work will promote the sustainable development and application of flexible electronics.