Comparative study of various nanocellulose enhanced freezing-tolerant, stretchable organohydrogels for versatile sensors

Abstract

Recently, ionic conductive organohydrogels (ICOs) have received widespread attention in wearable electronics. However, it remains challenging to combine reliable ionic conduction with good mechanical strength well, especially under extreme conditions. Herein, a novel ICO is produced by assembling polyvinyl alcohol with functionalized cellulose nanofibrils (CNFs) via a DMSO/H2O sol–gel process. A comprehensive study of the quaternized and carboxylated CNFs on ICOs is made. It is found that embedding of the latter can help ICOs to present excellent mechanical properties (tensile/compressive stress of 2.10/7.61 MPa), freezing tolerance (− 78 °C), and the highest electrical conductivity (3.23 S·m−1). Since all the primary alcohol carbons in the carboxylated CNFs have been thoroughly carboxylated, it is undoubted that their intermolecular attraction is sharply decreased to increase the counterion Na+ attraction, thus providing more hopping sites to enhance the ion transfer. Moreover, benefiting from these advantages, a human-interactive sensor based on the novel ICO is constructed to discern multiple human motions, including finger bending, wrist flexing, elbow bending, and walking. Overall, a facile yet versatile strategy is introduced that is expected to shed light on fabricating ICOs with all-around performance applicable in wearable electronics.