Light-Responsive Organic-Inorganic Hydrogel Functionalized with MoO₃ Composites of Poly(Vinyl Alcohol) and Choline Chloride-Based Polymeric Deep Eutectic Solvent

In this work, a polymeric deep eutectic template of poly(vinyl alcohol) and choline chloride in DMSO was used for the dissolution and preparation of inorganic MoO₃ composites. These were further incorporated into poly(acrylic acid) and acrylamide polymerized networks to form an organic-inorganic hydrogel. The characterization of the hydrogel shows that the rectangular-cubic-shaped microstructured inorganic composites were well dispersed on the surface of the hydrogel. More also, the pH-dependent swelling properties of the hydrogel show that the hydrogel increased by 285%, 583%, and 880% in acidic, neutral, and basic solutions respectively. Furthermore, the original transparent hydrogel displayed a distinct light blue coloration after UV-light irradiation for 5 s and eventually turned blue-black after 30 s. This color formation was accompanied by UV-Vis electronic absorption at 294 nm for the original hydrogel and a redshift to 304 and 320 nm after irradiation. The observed transitions could be associated with π→π^*/n→π^* transitions in the organic molecules or charge transfer transitions in the inorganic molecules. The promising light-responsive property of the hydrogel shows good prospects for optical display devices and photochromic materials.