Preparation and Properties of Multifunctional Nanocellulose-Reinforced PVA Ionic Hydrogel

Abstract

In this paper, polyvinyl alcohol (PVA), nanocellulose crystals (CNC), glycerol, and aluminum chloride hexahydrate (AlCl3·6H2O) were used to prepare PVA-CNC ionic conductive hydrogels by a one-pot freeze-thaw method. The microscopic morphology and internal structure of the hydrogel were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spec-troscopy (FTIR). The mechanical properties, electrical conductivity, and sensing properties of the hydrogel were tested by a universal material testing machine and LCR digital bridge, and the anti-freezing performance and water retention performance of the hydrogel were analyzed and compared. The results show that different concentrations of nanocellulose can significantly affect the mechanical strength of the hydrogel. When the content of CNC is 2%, the hydrogel has high tensile properties (elongation at break 384.29%) and firmness (up to 1.92 MPa). The open-circuit voltage of the hydrogel-based self-powered device can reach 0.815 V. In the bending sensing test, it was monitored that the resistance of the hydrogel changes rapidly at different bending angles, indicating that the hydrogel has good strain sensitivity. The addition of glycerol makes the hydrogel have high water retention rate, good mechanical properties and certain conductivity at −20 °C. The ionic conductive hydrogels prepared in this work have certain application potential in sensors, human-computer interaction, and flexible wearable devices.