الفهرس 
English CoverOnly 14 pages are availabe for public view
 |  | from | 119 |  |  |
| | | from | 119 | | |
Abstract
Smart products are materials that can respond to one or more external stimulus associated with changing their properties. A certain class of smart materials herein is the fluorescent and photochromic ink that can change color upon exposure to light. Fluorescent and photochromic anti-counterfeiting documents based on pigment screen-printing technology have recently attracted more interest owing to their tunable structure and potential application in different fields, such as sensors, logical gates, biological imaging, and security alerts. Herein, we develop a novel inorganic-organic hybrid photochromic and fluorescent ink for anti-counterfeiting documents using pigment/resin ink formula enclosing long-lived luminescent inorganic pigment distinguished with good thermal photostability. The produced ink exhibited optimal excitation wavelength at 360 nm with an absorption color and fluorescence changes of the printed document. To develop the transparent printed film from pigment/resin ink, the phosphorescent pigment has to be well-dispersed physically without agglomeration. The pigment/resin hybrid was applied effectively onto commercial cellulose paper sheets using screen- printing technology. The homogenous photochromic layer was deposited on cellulose paper document surface to afford considerable greenish-yellow as demonstrated by CIE coloration measurements under UV lamp, even at a pigment total content as low as 0.1 wt٪ of the ink formulation. The printed paper sheets exhibited three excitation bands at 235, 274 and 378 nm and three emission bands at 416, 418 and 436 nm. The fluorescence optical microscopy (FOM), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), Wavelength-Dispersive X-Ray Fluorescence Spectrometry (WDXRF) and energy-dispersive X-ray spectroscopic analysis (EDS) of the printed paper sheet were explored. The screen-printed paper sheets displayed a reversible and fast photochromism during ultraviolet irradiation without fatigue. The rheological properties, stability and printability of the ink were studied. Additionally, the promising optical properties including fluorescence and UV/Vis absorption spectra of this novel long-lived photoluminescent ink allowed to be applied as ink pads for advanced anti-counterfeit stamps.