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Photocatalytic activity of hydrothermal titanium dioxide
Lepičová, Martina ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
Hydrothermal synthesis is one of the most widely used methods for preparing nanoparticles of titanium dioxide. The process carried out at elevated temperatures and pressure, which facilitates the transformation of amorphous to crystalline titanium dioxide. Change of reaction conditions of the process (reactants concentration, temperature, time, pH, etc.) leads to change in morphology, microstructure and crystallinity of titanium dioxide nanoparticles. In this work the method of titanium dioxide preparation is briefly described. The titanium dioxide was prepared from a precursor titanium oxochloride and potassium hydroxide as the precipitating agent. Thus prepared titanium dioxide was immobilized on a glass substrate by material printing. This is a modern, highly precise and contactless method for preparing thin films. The photocatalytic activity of printed thin films of titanium dioxide was investigated by degradation of 2,6-dichlorindophenol at different irradiance. It was found that the sample prepared by hydrothermal treatment at 160 °C shows very similar photocatalytic activity to Degussa P25.
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Evaluation of pollutant impact on photographic images
Brablc, Tomáš ; Reháková, Milena (referee) ; Veselý, Michal (advisor)
This diploma thesis deals with the impact of pollutants on colour photography made by inkjet printing technology. There are summarized basic principles of inkjet printing, composition of inks and negative factors influencing the printout quality. The ozone was studied in the experimental part, because it has the stongest degrading effect of all common pollutants. The accelerated ageing test with changing the concentration of ozone and the time of exposure was performed. The test scales were made by using two different inks. The L*a*b* values and optical densities of selected fields were calculated from the reflectance spectra of 918 colour fileds. The colour gamut and its volume were calculated from the L*a*b* values. The changes of colour gamut volume correlated with the changes of optical densities. It emerged that using the colour gamut as the instrument of evaluation of the inkjet printout dyes degradation rate is eligible and it is suitable to recommend this method for the ozone accelerated tests.
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Sol-gel process using reverse micelles
Lukešová, Magdalena ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
Práce popisuje přípravu tenkých transparentních vrstev oxidu titaničitého metodou sol-gel procesu s reverzními micelami, které jsou jedinečným uskupením zajišťujícím uniformní velikost připravených částic. Neionogenní tenzid byl použit jako templát. Pomocí materiálového tisku, tedy specializovanou formou inkoustového tisku, byly připraveny tenké filmy oxidu titaničitého nanesením 1–4 vrstev. Po kalcinaci byly připravené vrstvy oxidu titaničitého charakterizované šířkou zakázaného pásu. Struktura vrstev byla popsána optickou mikroskopií a SEM. Fotokatalytická aktivita byla ověřena oxidační reakcí 2,6-dichlorindofenolu a rozkladem kyseliny stearové, která byla přímo natištěna na vrstvy oxidu titaničitého. Fotoindukovaná změna hydrofility byla studována pomocí měření kontaktního úhlu smáčení vody. Fotokatalytická účinnost připravených filmů rostla s počtem vrstev oxidu titaničitého.
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Inkjet prints ageing by ozone and light
Pasečná, Klára ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
This thesis is focused on the effect of ozone on ink-jet prints. The knowledge about print technologies, materials for ink-jet printing, influence of environmental factors on the prints degradation and the methods of print lifetime estimation are discussed in the theoretical part of the thesis. Test-charts of 108 samples of C, M, Y primary colours and their overprints were prepared. I used two types of papers designed for ink-jet printing. These samples were exposed the effect of ozone in various concentrations to perform an accelerated aging experiment. Optical density values, La*b* coordinates, colour difference values were calculated from the measured spectral data. Changes of colours of the ink due to ozone exposure were determined and discussed. The validity of the reciprocal law due to ozone exposure was studied, too. The reciprocal behaviour was not confirmed for both types of the studied papers.
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Lightfastness of inkjet prints
Buteková, Silvia ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
The stability of inkjet print is influenced by a lot of factors. Just the surrounding environment in image stability plays an important role. When the prints fade, not only this does occur by light exposure, but also considerable effect has relative humidity, ozone and other air pollutants. The types of receiving layers or ink composition belong to other factors, which affect the stability of prints. This diploma thesis deals with the long-term ageing of digital prints produced by ink jet technology. The study of resistance of inkjet prints was realized on nine different types of media. Samples were prepared with use of dye-based and pigment-based inks. The attention was especially focused on the influence of light on print durability, but study was also oriented on the impact of ozone. The samples were exposed to the indoor daylight. Changes in printed colours were measured and evaluated in colorimetric quantities. In this study of inkjet prints degradation the dependence of colour gamut volumes on UV and VIS exposure dose was evaluated.
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Self-assembled layers based on silicon
Bábík, Adam ; Veselý, Michal (referee) ; Čech, Vladimír (advisor)
Thin film deposition, characterization and properties of self-assembled monolayers based on silicon were studied with emphasis on the SA monolayers deposited from vinyltriethoxysilane and vinyltrichlorsilane. The thesis is aimed at basic properties of the SA monolayer and explanation of its growth. Methods and techniques used for analysis of the monolayer were described as well. Contact angle measurements and an evaluation of the surface free energy are depicted in details. The deposited SA layers were observed with respect to their chemical composition and surface morphology by X-ray photoelectron spectroscopy (XPS), ellipsometry and atomic force microscopy (AFM).
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Photocatalytic Activity of Titanium Dioxide Printed Layers
Novotná, Michaela ; Jančovičová, Viera (referee) ; Veselý, Michal (advisor)
This diploma thesis was focused on the preparation of self-cleaning and photocatalyticaly active titanium dioxide thin films. Transparent and porous thin layers of titanium dioxide were prepared from sol-gel containing titanium tetraisopropoxide (TTIP) as precursor with addition polyethylene glycol (PEG). Transparent thin layers of titanium dioxide were also prepared from colloidal solution titanium dioxide. The immobilization of thin titanium dioxide layers was performed by a sol-gel process on the soda lime glasses. Diffusion of sodium cation from soda lime glasses into titanium dioxide layer were blocked. Sol was deposited by printig method – micropiezo deposition. Sol and thin titanium dioxide layers were characterised by the physical-chemical method. For prepared sol viscosity, density and surface tension were measured. Thickness and hydrophilicity of titanium dioxide layers also were studied. The photocatalytic activity of the printed titanium layers were tested via the photocatalytic degradation of the 2,6-dichlorindophenol. The influence of addition PEG into the sol and influence of sol loading was studied. It was found that the addition of PEG into the sol significantly increased the photocatalytic activity of titanium dioxide layers.
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Study of Inkjet Inks Degradative Processes
Samcová, Kateřina ; Čeppan, Michal (referee) ; Veselý, Michal (advisor)
This diploma thesis follows the degradation of inkjet print by ultraviolet radiation and ozone effect for different types of papers. Colour test charts for the evaluation of accelerated ageing effect of ultraviolet light and gas fading were designed. These test charts were printed by dye-based inks on selected receiving media and exposed to ozone-enriched environment, UV radiation and their combination. The colorimetric values L* a* b* were calculated from spectral data of all patches of the test charts. The ozone effect on the prints was evaluated in the terms of total colour difference and dye concentration. The degradation of dye caused by ozone was observed also in a long-term period, after the contact of sample with ozone was terminated. Results of printed samples accelerated ageing by UV radiation and those that were influenced by the ozone effect were evaluated in the same way. It was found out that UV radiation and ozone treatment have a different effect on the degradation of dyes. The degradation rate is also strongly influenced by the receiving layer composition of papers used for inkjet printing. Also the catalytic effect of dyes was evaluated.
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Study of thin film organic materials thickness
Hegerová, Lucie ; Veselý, Michal (referee) ; Zmeškal, Oldřich (advisor)
The diploma thesis deals with the determination of thickness and refractive index of thin organic films using image analysis. In the theoretical part there are described principles of the methods, which are used to prepare the films (spin coating, inkjet printing, vapour deposition), the characteristics of thin films, ways of finding out the thickness and refractive index of substances (weight methods, electric methods, method based on measurement of absorption coefficient of light, interference microscopy, ellipsometry) and also image analysis (harmonic and wavelet analysis). Interference microscope Epival - Interpako (Carl Zeiss Jena), digital camera Nikon Coolpix 5400 and computer were used for the determination of thickness and refractive index. The thicknesses of layers were set on the basis of interference images of edges and grooves – both from the side of the metal contact and the side of underlying glass. The refractive indices of thin layers were then set using the recorded figures. In the final part of the thesis there are discussed the results of interference images photographed along the full length of the aluminium contact which are used for measuring electrical characteristics of DPP structures. The produces are thicknesses and refractive indices of individual layers.
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Optical sensor for UV radiation
Třešňáková, Andrea ; Drbohlavová, Jana (referee) ; Veselý, Michal (advisor)
This bachelor thesis deals with monitoring of photocatalytic activity on prepared optical sensors for UV illumination. A polymeric matrix was prepared based on the redox dye Acid Red 1, titanium dioxide and calibration agents. The deposition of matrix was done by material printing – roll-to-roll printer – on PET film. This resulted in optical dosimeter for UV illumination. Finally, the validity of the reciprocity law was proved.
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