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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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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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Separation of liquid crystal forming substances using non-aqueous capillary electrokinetic chromatography
Čokrtová, Kateřina ; Křížek, Tomáš (advisor) ; Kubíčková, Anna (referee)
Liquid crystals are widely used in electronics, medicine and other fields. Analytical separations are important in the development of new liquid crystals to control the purity of synthesized substances. The sample analysis is important for detection of impurities formed during synthesis and for determination of chiral purity of the substance. Liquid crystal-forming substances cannot be separated by capillary zone electrophoresis due to the absence of readily ionizable groups. Electrokinetic chromatography is a method in which a suitable surfactant is added to the background electrolyte. The uncharged substances then interact with the electrically charged surfactant to obtain an effective charge. Separation can occur if they interact differently with the added surfactant. Another problem complicating the analysis is the very low solubility of analytes in water. Separations in this work were therefore carried out under non-aqueous conditions in acetonitrile. However, under these conditions a poor repeatability of the migration times of the substances was observed. Therefore, capillaries with differently coated inner walls were used in subsequent measurements. Surface modification should improve the repeatability of migration times. Several types of capillary coating have been tested. Dynamic coating...
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Self-assembly of polymers with amphiphilic compounds (surfactants) in aqueous solutions
Delisavva, Foteini ; Procházka, Karel (advisor) ; Štěpánek, Petr (referee) ; Pánek, Jiří (referee)
Title: Self-assembly of polymers with amphiphilic compounds (surfactants) in aqueous solutions Abstract: This PhD Thesis is devoted to the co-assembly in systems containing electrically charged polymers (polyelectrolytes and block copolymers containing polyelectrolyte sequences). I studied the interactions between block copolymers and oppositely charged surfactants in aqueous solutions, and the structure and properties of co-assembled nanoparticles by a combination of several experimental methods. I found that the spontaneous formation, solubility and stability of complex nanoparticles depend not only on the electrostatic attractive forces but also on the hydrophobic effects. In a major part of my Thesis, I studied the interaction of polyelectrolytes with oppositely charged gemini surfactants (containing two charged head-groups interconnected by a short linker and two hydrophobic tails) which is a relatively new topic - much less studied than the co-assembly with conventional single tail surfactants. Better understanding of the formation and properties of complexes containing gemini surfactants and polymers provides knowledge that should lead to novel tailor-made nanoparticles with desired properties for applications in medicine and new technologies (including nano-technologies). We have shown that the...
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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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