Preparation of photochromic hydrogel toward anticounterfeiting and duplicable data encryption applications

Traditional inks have shown drawbacks, such as low efficiency, low photostability, high cost, and poor durability. Self-healing hydrogels have been more robust and durable than traditional inks. In the current study, a hydrogel ink was prepared from a combination of cellulose microfibrils (CMF; a dispersion agent and microfiller), carboxymethylcellulose (CMC; a hosting agent), and rare-earth strontium aluminate nanoparticles (SAN; a photoluminescent agent). CMF was prepared from sugarcane bagasse, which is a type of agricultural waste. The use of CMF as a dispersion agent and microfiller prevented the agglomeration of SAN. To develop a colorless stamp, SAN must be uniformly dispersed in the nanocomposite hydrogel (CMF@CMC). Different SAN concentrations were combined with CMF and CMC to produce different optical properties. Using transmission electron microscopic (TEM) analysis, CMF has diameters ranging from 15 nm to 50 nm, whereas the SAN morphology demonstrated diameters of 8 nm to 17 nm. The colorimetric coordinates and luminescence spectra showed a color change to green when exposed to ultraviolet radiation. The stamped sheets were excited at 375 nm to produce an emission intensity at 519 nm. The mechanical behavior of stamped papers and the rheological performance of hydrogels were investigated. The morphology of the hydrogel films was explored. The current hydrogel consists of a photostable, reversible, durable, and photochromic nanocomposite, offering a dependable anticounterfeiting solution for a range of commercial merchandise, such as banknotes and commercial products.