Abstract

A novel photochromic and self-bleaching hydrogel was prepared based on the Cu-doped tungsten oxide (WO 3 ) hybrid encapsulated in the co-polymer matrix polymerized using acrylamide (AM) and hydroxyethyl acrylate (HEA) as monomers. The Cu-WO 3 -25 % hybrid was generated by introducing Cu species into the lattice of WO 3 with hexagonal-like prismatic structure and acted as light absorber. Given that WO 3 and Cu-doped WO 3 hybrids possess superior water solubility by using water and deep eutectic solvents (DESs, ChCl:EG) containing sufficient hydrogen bond as co-solvent, the high transparency of 90 % of the hydrogels was achieved. As compared with P(AM-HEA)-WO 3 -based hydrogel, the P(AM-HEA)-Cu-WO 3 -X hydrogel exhibited the enhanced coloration degree under UV irradiation. The P(AM-HEA)-Cu-WO 3 -25 % photochromic hydrogel changed from colorless to blue immediately once illuminated by UV light, and turns into dark-blue with the irradiation time going on. The self-bleaching process indicates it only takes 40 min for the P(AM-HEA)-Cu-WO 3 -25 % hydrogel to return to the original colorless transparent state. Furthermore, the hydrogel systems exhibit efficient antibacterial activities against bacteria of both E. coli and S. aureus , accompanying with outstanding biocompatibility. As such, the fabricated hydrogel demonstrates rapid photoresponse, self-bleaching process, superior antibacterial performance, and cell viability, showing a great potential application as stimuli-responsive materials.