Low-Water-Content Lignosulfonate Gels with Dense Triple Hydrogen-Bonding Networks for Wearable Sensors and Photothermal-Electric Conversion

Abstract

Achieving mechanical robustness, efficient ion transport, environmental tolerance, and energy conversion in a sustainable soft conductor remains challenging. Herein, a low-water-content supramolecular gel (PLPG) was fabricated via evaporation-induced co-assembly of poly(vinyl alcohol) (PVA), phytic acid (PA), and lignosulfonate (LS). Evaporation reconstructed a ternary hydrogen-bonding network. At an optimized LS content, PLPG-L0.5 exhibited 267 kPa tensile strength and 0.2676 S m−1 ionic conductivity, retaining flexibility and conductivity after 7 days at −20 °C. As a strain sensor, it showed electrical responses after 3000 s cyclic loading tests and enabled monitoring of human motion. The aromatic conjugated structure of LS allowed rapid heating above 65 °C under solar irradiation (0.1 W cm−2). Integrated with a thermoelectric generator, the system tuned the electrical output with light intensity and drove a miniature fan. This offers a strategy for lignin-based soft materials integrating wearable sensing and photothermal energy conversion.