Stretchable, freezing-tolerant conductive hydrogel for wearable electronics reinforced by cellulose nanocrystals toward multiple hydrogen bonding

Abstract

Conductive hydrogels have the mechanical properties and the electronic transport properties of conductive polymers, which have been widely used in the fields of energy storage and bioelectronics. However, the rigidity and brittleness of conductive polymers hinder the long-term stability of hydrogels and limit its application in new flexible electronic devices. It is a high challenging task to prepare ion-conductive hydrogels with excellent mechanical properties, anti-freeze and electrical conductivity through a simple preparation process under the action of hydrogen bonds. We present a facile strategy to prepare mechanically tough, swelling ability hydrogels reinforced by cellulose nanocrystals (CNCs). Herein, CNCs were produced by high pressure homogeneous and pretreated with deep eutectic solvent (DES). The conductivity of the hydrogel is 0.021 S/cm at room temperature. Due to the function of DMSO/H2O in organic solvent system, the ion-conducting hydrogel remains flexible and conductive (0.014 S/cm) at −70 °C. Hydrogel has excellent mechanical properties (stress about 1.4 MPa, strain about 1018%), excellent transparency, freezing resistance (−70 °C) and other comprehensive characteristics. The hydrogel can be assembled into a sensor for use in monitoring large and small movements of the human body, showing good responsiveness and stability.