Sodium Lignosulfonate-Induced Rapid Gelation of Multifunctional Hydrogels for Flexible Strain Sensors

Conductive hydrogels have demonstrated significant potential in flexible electronics due to their adjustable flexibility and remarkable sensitivity. However, the development of flexible wearable electronic devices may be impeded by the time-consuming and energy-consuming polymerization process of hydrogels. In this study, a sodium lignosulfonate-Al3+ (LS-Al3+) self-catalytic system was designed to efficiently decompose ammonium persulfate (APS) at 25 °C within 9 min, initiating rapid polymerization of acrylic acid (AA) monomers. Benefiting from strong physical and chemical cross-linking, the hydrogel demonstrates excellent mechanical properties (elongation: 1753%; tensile stress: 0.139 MPa). Furthermore, the prepared hydrogel exhibits UV-blocking ability, antibacterial activity, freezing tolerance, high ionic conductivity (0.648 S/m) sensitivity along with near real-time response (252 ms) and notable thermosensitive behavior. When applied as flexible strain sensors, they can accurately real-time and accurate monitoring of both large-scale and subtle human motions. These features highlight its promising potential for wearable strain-sensing applications. The strategy proposed here pave the way for efficient and eco-friendly preparation of advanced hydrogel materials.