Fabrication of photochromic and electrochromic (PVP-am)/WO3/MoO3 hydrogel composites and glass films with programmable shapes

Recently, the fabrication of functional and stimuli-responsive hydrogels using deep eutectic solvent derivatives is gaining tremendous scientific recognition owing to their unique self-switching properties. In this study, perfluorinated deep eutectic mixtures were prepared as the template for the synthesis of WO 3 /MoO 3 composites. The metal oxide-based composites were further employed as a chemical crosslinking agent for the polymerization of polyvinyl pyrrolidine (PVP) and acrylamide (Am), for the construction of (PVP-Am)/WO 3 /MoO 3 hydrogel composites. The hydrogels displayed unique morphologies and mechanical properties . The hydrophilic nature of hydrogels as well as the high concentration of dispersed WO 3 /MoO 3 composites in the polymer network contributes to their photochromic activity and allows an immediate coloration upon exposure to light at a short time. Howbeit, the low concentration of the dispersed WO 3 /MoO 3 composites in the dry glass membrane is responsible for the blue coloration and an extended time of photochromic response. In addition, the electrochromic behavior of the hydrogel composites displayed a strong quasi-rectangular shape potential window as well as a well-defined redox cyclic voltammetry curve when exposed to high voltage. This could be due to the photoredox property of the WO 3 /MoO 3 composites responsible for charge transfer between the different oxidation states.