Three birds, one stone: A multifunctional POM-based ionic hydrogel integrating strain sensing, fluorescent and antibacterial properties

Fluorescent hydrogels have garnered significant research interest in information storage fields due to their unique physicochemical properties and design versatility. However, the relatively limited functionality of most fluorescent hydrogels also restricts their practical application. Therefore, the development of multifunctional stimuli-responsive hydrogels has become increasingly urgent. In this context, a multifunctional POM-based ionic hydrogel with high conductivity, fluorescence and antibacterial properties was prepared by simple one-step radical polymerization using acrylamide, polyoxometalates (POMs) and imidazole ionic liquid (1-butyl-3-ethenylimidazol-1-iumbromide) as raw materials. The fabricated multifunctional POM-based ionic hydrogel exhibits prominent fluorescence emission, superior ionic conductivity (11.22 mS/cm), and remarkable antibacterial activity against Gram-positive/negative bacterial strains, including Escherichia coli ( E. coli , 91.96 %) and Staphylococcus aureus ( S. aureus , 99.89 %). Based on these advantages, the multifunctional stimuli-responsive POM-based ionic hydrogel not only exhibit excellent sensing properties for motion recognition, but also demonstrate reversible luminescent switching behavior under HCl/NH 3 stimulation. This reversible luminescent switching property makes the hydrogels promising candidates for secure information storage. Notably, the usage information remains invisible in daylight and can only be clearly observed under ultraviolet light, highlighting its potential applications in information protection. This work not only realizes the simple synthesis of multifunctional POM-based ionic hydrogel, but also provides a novel idea for developing ionic hydrogel as wearable sensors.