Novel Lignin Hydrogel Sensors with Antiswelling, Antifreezing, and Anticreep Properties

Hydrogel shows great potential as a flexible wearable electronic device. However, the practical application of hydrogel is still significantly limited due to the poor functional stability caused by swelling behavior, non-frost resistance caused by high water content, and obvious creep behavior under repeated external force. In this work, macromolecular lignin with a three-dimensional network structure, and active functional groups are introduced into the hydrogel through the esterification grafting reaction of methacryloyl chloride. The introduction of lignin effectively improves the antiswelling, antifreezing, and creep resistance of the hydrogel sensor, while maintaining the mechanical properties (elongation at break > 350%, tensile strength > 1.5 MPa) and electrical conductivity (10 S/m). Under extreme environments, the toughness, tensile strength, and elongation at break of the hydrogel remain at more than 96%. Furthermore, the antifreezing, creep resistance, and conductivity of hydrogel sensors are not significantly affected after immersion in water for a long time (72 h). This work proposes a simple strategy to improve the antiswelling, antifreezing, and anticreep properties of hydrogels, which has guiding significance for the preparation of high-performance flexible wearable electronic materials.