Fluorescent Double Network Hydrogels with Ionic Responsiveness and High Mechanical Properties for Visual Detection

We developed a fluorescent double network hydrogel with ionic responsiveness and high mechanical properties for visual detection. The nanocomposite hydrogel of laponite and polyacrylamide serves as the first network, while the ionic cross-linked hydrogel of terbium ions and sodium alginate serves as the second network. The double-network structure, the introduction of nanoparticles and the reversible ionic cross-linked interactions confer high mechanical properties to the hydrogel. Terbium ions are not only used as the ionic cross-linked points, but also used as green emitters to endow hydrogels with fluorescent properties. On the basis of the “antenna effect” of terbium ions and the ion exchange interaction, the fluorescence of the hydrogels can make selective responses to various ions (such as organic acid radical ions, transition metal ions) in aqueous solutions, which enables a convenient strategy for visual detection toward ions. Consequently, the fluorescent double network hydrogel fabricated in this study is promising for use in the field of visual sensor detection.