Smart materials allow predictable and useful attribute variations based on external stimuli. With photocatalytically active substances, we can observe photocatalysis, i.e., proportional color changes relative to the amount of UV and/or visible light exposure. One possible application is the preparation of a photocatalytically active printing ink, which would serve as an indicator, warning the user of potentially dangerous exposure to UV light. The reversibility of the photocatalyctic reaction is an important factor in photocatalytically active printing inks, as it ensures a reusable indicator. Such indicators have a variety of uses due to their convenience (e.g., UV exposure indicative clothing) and ease of use. Public-health improvements and treatment-cost reduction with diseases that arise from UV over-exposure, as well a higher level of consumer protection from UV-sensitive merchandise such as oils, are just a few of the possible applications.
The purpose of this thesis is the preparation of a functional printing ink based on the indicator dye resorufin, which decolorizes in proportion to the amount of UV exposure. In the presence of oxygen and the absence of light, a reverse reaction occurs and resorufin re-colorizes. The printing ink was prepared using polyvinyl alcohol, a photocatalyst, an indicator dye, water as the solvent, as well as some other additives. Basic trials have been made for the preparation of a suitable ink composition. The dye was applied with an automatic dye applicator (Elcometer 4340). The resulting color changes were colorimetrically analyzed. Research was conducted on the relationship between different electron donors (xylitol, glycerol, sobitol and glycol) and different substrates (paper board Leneta and overhead projector foil) on the basic properties of the photocatalytic printing ink.
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