Thesis (M.Sc.) - Cairo University - National Institute of Laser Enhanced Sciences (NILES) - Department of Laser Application in Enviromental Metrology, Photochemistry and Photobiology

Fabrication of photochromic inks are gaining much research interest as they have many diverse applications such as photovoltaic, bio-medical, and anti-counterfeiting. New photochromic film was developed for the preparation of anti-counterfeiting documents utilizing inorganic/organic nanocomposite enclosing a photoluminescent inorganic pigment and a polyacrylic binder polymer.The produced nanocomposite exhibited a fluorescent color change with an optimum excitation wavelength at 358 nm.To generate a translucent film from pigment/polyacrylic nanocomposite, the phosphorescent strontium aluminium oxide pigment should be well-dispersed in the solution of the polyacrylic-based binder without agglomeration.The photochromic nanocomposite was applied efficiently onto commercial cellulose paper documents utilizing the effective and economical spray-coating technology followed with thermofixation. A homogeneous photochromic film was immobilized onto cellulose paper surface to introduce a transparent film changing to greenish-yellow upon exposure to ultraviolet light as depicted by CIE coloration measurements.The photochromic effect was monitored at lowest pigment concentration (0.25 wt%). The spray-coated paper documents exhibited two absorption bands at 256 and 358 nm as well as two fluorescence peaks at 433 and 511 nm

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