Lanthanide-Coordinated Multifunctional Hydrogel for Detecting Human Motion and Encrypting Information

Abstract

Smart hydrogels with multi-fluorescent properties hold great promise for information encryption. However, conventional fluorescent hydrogels often lack adequate mechanical properties and multiple responsiveness, limiting their range of applications. In this study, a multifunctional hydrogel featuring an interpenetrating polymer network (IPN) composed of poly(vinyl alcohol) (PVA) and poly(acrylic amide-co-2-acrylamido-2-methylpropane sulfonic acid) P(AM/AMPS) chemical cross-linking networks is designed. Through the coordination of lanthanide ions (Eu³⁺, Tb³⁺) and glycine, the hydrogel achieves exceptional stretchability (over 900%) and adjustable photoluminescence properties. Due to the sulfonic acid groups on 2-acrylamide-2-methylpropanesulfonic acid (AMPS), which support various noncovalent interactions, the PVA-P(AM/AMPS)-Gly-Ln³⁺ hydrogel displays strong and reversible adhesive properties on diverse substrates. Ultimately, the hydrogel is assembled into a multifunctional, flexible sensor, boasting satisfactory sensitivity (GF = 5.3), rapid response rate (100 ms), and outstanding photoluminescence characteristics, highlighting its potential for applications in human motion detection and information encryption.