Tough lanthanide luminescent hydrogel for nitroaromatics detection

Abstract

Luminescent hydrogels have received considerable attention in the application of sensors. Nitroaromatics are harmful to human health and can be carcinogenic. Some skin allergies and central nervous system injuries may also be attributed to the over exposure to nitroaromatics. Thus, nitroaromatics sensor with fast detection and low detection limit is highly desirable. Herein, novel tough hydrogels were prepared by introducing hydrogen bonds and covalent bonds into the interpenetrating networks of modified chitosan and poly(vinyl alcohol) (PVA) via frozen-thawing induced chemical cross-linking. The synthesized hydrogels exhibit high mechanical strength (0.23 MPa tensile strength at 140% tensile strain, 1.0 MPa compressive strength at 80% compressive strain). Strong green emission was realized by energy transfer from the modified chitosan to Tb3+ via the so-called “antenna effect.” The prepared luminescent hydrogels show an excellent detection effect on nitroaromatic compounds and its detection limit can reach ppm-level. The hydrogels also exhibit good reversibility and a fast “off–on” fluorescence switching process. This work may open up a new way for the development of stable, rapid, and reusable sensors for the detection of harmful nitroaromatics.