Schiff base fluorescent hydrogel containing acylhydrazone structure and pyridine ring with multifunction

Abstract

AbstractIn order to prepare multifunctional fluorescent hydrogel (FH), functional Schiff base ligands have been incorporated into polymer networks. We reported here a novel multifunctional Schiff base functionalized FH, P(AM‐PEGA‐PEPMA), and its corresponding metallohydrogel, Zn2+‐P(AM‐PEGA‐PEPMA), which exhibited tunable fluorescence intensity, self‐healing ability, stretchability, and shape‐memory property. P(AM‐PEGA‐PEPMA) was obtained by one‐pot micellar copolymerization and Zn2+‐P(AM‐PEGA‐PEPMA) was formed by metal coordination between Schiff base ligand (PEPMA) and Zn2+. Zn2+‐P(AM‐PEGA‐PEPMA) hydrogel was obtained after cross‐linking by the PEPMA‐Zn2+ metal coordination, whose maximum tensile strain can reach over 900%. The fluorescent intensity of Zn2+‐P(AM‐PEGA‐PEPMA) hydrogel gradually increased with the increase of Zn2+ concentration ([Zn2+]). When [Zn2+] was 0.1 M, it could reach to 400% of the original fluorescence intensity. The reversible fluorescence change of hydrogel can be controlled by Zn2+ together with pH. What's more, the Zn2+‐P(AM‐PEGA‐PEPMA) hydrogel has the ability to self‐heal within a minute at room temperature. The shape of the P(AM‐PEGA‐PEPMA) hydrogel was memorized/restored by the forming/breaking the metal coordination between PEPMA and Fe3+. With above properties, P(AM‐PEGA‐PEPMA) hydrogel and Zn2+‐P(AM‐PEGA‐PEPMA) hydrogel are expected to be applied for encryption, flexible sensors and soft wearable devices.