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Analysis of the properties of liquid crystalline materials
Bodeček, Martin ; Rozsívalová, Zdenka (referee) ; Frk, Martin (advisor)
Master´s thesis covers introduction to the problems of materials with specific proprieties named liquid crystals. Theoretic part features primary fission these materials, theirs mechanical, electrotechnical and optical characteristics. Interesting chapter is description choice application including perhaps most interesting using liquid crystals - liquid crystal display. In this trend continues experimental part too, where there are first mentioned characteristics LCD, and after it alone metering capacitive characteristics display with active matrix. Main attention in experiment is however concentraded on evaluation frequency analysis of components complex permittivity regarding in plant temperature on submitted sample liquid crystals.
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Using thermochromic systems for testing heat distribution
Klimeš, Jan ; Sedlaříková, Marie (referee) ; Zatloukal, Miroslav (advisor)
This thesis deals with principles of thermochromism and its possible applications in heat distribution testing. Theoretical part describes mechanisms which allow the thermochromic properties of the substances. Particular attention is paid to cholesteric liquid crystals. Ability to measure the heat for this type of liquid crystals was varified. Also long service life in high humidity environment, enviroment with intense UV radiation, cyclic changes in temperature or immersion in water was tested. A possibility of their practical use in diagnosis was verified as well. Specifically mapping of heat distribution on an assembled PCB. Conclusion contains comparison and evaluation of this method in terms of accuracy, user comfort and economic advantages compared to conventional infrared sensors.
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Fresnel Incoherent Correlation Holography (FINCH)
Bouchal, Petr ; Slabý, Tomáš (referee) ; Chmelík, Radim (advisor)
In the Bachelor's thesis, the recently proposed method known as Fresnel Incoherent Correlation Holography (FINCH) is examined both theoretically and experimentally. Its main advantage consists in a possibility to realize holographic reconstruction of 3D objects illuminated by incoherent light. In FINCH, the object recording is performed applying methods of optical holography and digital diffractive optics. The object reconstruction is realized numerically and utilizes principles of digital holography. In experiments, the modern optoelectronic devices known as Spatial Light Modulators are effectively used. The Bachelor's thesis includes a short review including description of the basic principles of FINCH but its own contribution consists in the mathematical description of the method and creation of the numerical simulation model in Matlab. The main result of the thesis is design and realization of experiments enabling verification of the method. In the Bachelor's thesis, results of two independent experiments realized with different types of Spatial Light Modulators HOLOEYE and HAMAMATSU are presented. An agreement of experimental results with theoretical predictions is very good. A short discussion of the obtained results, further research topics and FINCH applications is also included in the Bachelors's Thesis.
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Enantioseparations of liquid crystalline materials
Vaňkátová, Petra ; Kubíčková, Anna (advisor) ; Čabala, Radomír (referee) ; Kohout, Michal (referee)
(EN) Liquid crystalline materials are an important domain of the material science. Chiral liquid crystals (CLCs) are researched for their unique chirality-derived properties. The development of new CLCs focuses both on appropriate molecular design to fit their intended purpose and also on ways of using widely available and less expensive sources of chirality to enable cost- effective production for a potential large-scale production. Methods capable of enantioseparation are needed mainly for chiral purity control of newly synthesized CLCs and for their potential use in scaling up for preparative purpose. Nowadays, enantioselective chromatography has evolved to be the method of choice for enantioseparations. This thesis aims to establish new approaches to chromatographic enantioseparations of CLCs by developing fast and robust enantioselective methods using two different ultra-high performance chromatographic techniques - sub/supercritical fluid chromatography (UHPSFC) and liquid chromatography (UHPLC). UHPSFC is introduced and successfully employed for the first time for this purpose. For some CLCs, high values of enantioselectivity and enantioresolution were achieved, opening the possibility of scaling up to semipreparative use. In UHPLC, two modes (reversed-phase and polar organic solvent mode)...
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Polar liquid crystals: structures, phase transitions and properties
Podoliak, Natalia ; Novotná, Vladimíra (advisor) ; Perkowski, Pawel (referee) ; Valentová, Helena (referee)
In the thesis the structure-property relations of newly synthesised liquid crystalline compounds have been investigated with respect to the length of the non-chiral chain, number of lactate units or the lateral substitutions in the molecular core. Such promising for applications phenomena as orthoconic properties and de Vries behaviour have been found and studied for certain compounds. Besides, the antiferroelectric, TGB, hexatic phases have been observed for some compounds of the studied series. Such unique phenomenon as re-entrancy has been observed for a few compounds of the series under investigation and binary mixtures of one compound with neighbouring homologues have been prepared and studied.
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Modeling of anisotropic viscoelastic fluids
Šípka, Martin ; Tůma, Karel (advisor) ; Průša, Vít (referee)
In this thesis, we aim to create a framework for the derivation of thermodynamically consistent anisotropic viscoelastic models. As an example we propose simple models extending the isotropic Oldroyd-B and Giesekus models to illustrate the models' behavior and the process of finding the correct equations. We show what behavior in sheer we can expect and continue with a 3D simulation inspired by the experiment on a real liquid crystal mixture. Finally, we compare the simulation and the experiment to find similarities and possible further research topics.
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Oriented copolymers with liquid crystalline building blocks
Horodecka, Sabina Jolanta ; Strachota, Adam (advisor) ; Uchman, Mariusz Marcin (referee) ; Sedláková, Zdeňka (referee)
Several series of reversible physical networks based on polydimethylsiloxane (PDMS) chains and liquid crystalline (LC) structural units were synthesized and studied, which belong to three different architecture types: (1) LC-grafted PDMS (with LC quartets at the grafting sites), (2) LC-end-capped linear PDMS, (3) and linear 'infinite' LC-PDMS copolymers (with alternating LC and PDMS segments). PDMS spacers of different lengths of were tested, as well as 6 different polyaromatic mesogens of azo type and azo-free type. Hydrosilylation coupling of vinyl-functional mesogens, obtained as part of an international cooperation, with commercial Si-H-functional PDMS was employed to synthesize all the studied materials. The copolymers were physically crosslinked by the nano-aggregation of the LC units contained in their macromolecules. The thermotropic properties of the LC-nano-aggregates lent interesting physical properties to the whole material, making some of the copolymers attractive as potential smart materials. The PDMS spacer segments were selected for the sake of their extreme flexibility, which should provide elastic properties to the physically crosslinked copolymers, and also because of their (desired) incompatibility with the mesogens. This latter effect was highly helpful for achieving the...
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Separation of chiral compounds
Šrolerová, Tereza ; Kubíčková, Anna (advisor) ; Křížek, Tomáš (referee)
This bachelor thesis deals with the chiral separation of newly synthesized orthoconic antiferroelectric liquid crystals using ultra-high performance liquid chromatography. These studied compounds differ in the alkyloxy-spacer length, in the presence and/or position of the fluorine atom on the phenyl ring and in the chiral center. The separation took place in a reverse separation mode using a chiral stationary phase based on derivatized amylose. First, the effect of mobile phase flow rate and column temperature on separation efficiency was exanimated. The effect of the composition of the mobile phase on the enantioseparation were studied at the optimum temperature and flow rate. The mobile phase was based on acetonitril, while deionized water was added gradually using isocratic elution. Furthermore, the effect of chromatographic conditions and the structure of the studied analytes on resolution and enantioselectivity was investigated, concretely the presence and position of fluorine atom on pfenyl ring, the length of alkyloxy-spacer and the effect of divergent chiral center. Under optimized chromatography conditions we succeeded to separate all examined substances on the base line. Key words: ultra-high performance chromatography, liquid crystals, enantioseparation, chiral stationary phase, reverse mode
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Modeling of anisotropic viscoelastic fluids
Šípka, Martin ; Tůma, Karel (advisor) ; Průša, Vít (referee)
In this thesis, we aim to create a framework for the derivation of thermodynamically consistent anisotropic viscoelastic models. As an example we propose simple models extending the isotropic Oldroyd-B and Giesekus models to illustrate the models' behavior and the process of finding the correct equations. We show what behavior in sheer we can expect and continue with a 3D simulation inspired by the experiment on a real liquid crystal mixture. Finally, we compare the simulation and the experiment to find similarities and possible further research topics.
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Chiral separations of orthoconic antiferroelectric liquid crystals
Archuleta, Natália ; Kubíčková, Anna (advisor) ; Kozlík, Petr (referee)
This study reports chiral separation of orthoconic antiferroelectric liquid crystals using ultra-high performance liquid chromatography. The materials studied in this paper differ in the presence and/or position of the fluorine atom on the phenyl ring and in the alkoxy-spacer length. Reversed non-aqueous mode using chiral stationary phase based on derived polysaccharides was used. In the first part of the thesis, the effect of the mobile phase flow rate and the column temperature on the enantioseparation efficiency was observed. Subsequently, under optimum flow rate and column temperature, the effect of mobile phase composition was examined. The mobile phase was based on acetonitrile, while various ratios of methanol, ethanol or isopropanol were added using isocratic elution. Two chromatographic columns containing different chiral stationary phase were compared - CHIRALPAK® IA-U amylose tris(3,5-dimethylphenylcarbamate) and CHIRALPAK® IG-U amylose tris(3-chloro-5-methylphenylcarmabate). We studied the influence of chromatographic conditions and analyte structure on resolution, enantioselectivity and retention. Key words: ultra-high performance liquid chromatography, enantioseparation, liquid crystals, reversed phase
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