Regenerated cellulose hydrogel with excellent mechanical properties for flexible sensors

Cellulose-based hydrogels are promising materials for the rapid development of flexible sensors. However, the further application has been limited due to their poor mechanical properties. In this study, we improved the microstructure and mechanical properties of cellulose-based hydrogels by dissolving cellulose in an AlCl3/ZnCl2 composite solution and inducing interactions between cellulose molecules through a regeneration process. The crystal structure of cellulose changed from original cellulose I to cellulose II via dissolution and regeneration process. The crystallinity of regenerated cellulose was significantly affected by the composition of regenerated solvents, and the crystallinity of regenerated cellulose using water (61.42%) was higher than that using anhydrous ethanol (40.17%). By adjusting the mass ratio of ethanol/water solution, the tensile strength and elongation at break of the cellulose hydrogel could reach 2.38 MPa and 196%, respectively. In addition, the regenerated cellulose hydrogel exhibited excellent electrical conductivity, making a promising material in flexible sensing devices.