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Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems
Radecki, Marek ; Hanyková, Lenka (advisor)
Title: Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems Author: Marek Radecki Department: Department of Macromolecular Physics Supervisor: Doc. RNDr. Lenka Hanyková, Dr., Department of Macromolecular Physics Abstract: In this thesis, the temperature-induced phase transition in liner polymer solutins and hydrogels of semi-interpenetrating (SIPNs) and interpenetrating (IPNs) polymer networks was studied with respect to various composition, network architecture and procedure. Thermoresponsive linear polymers based on poly(vinyl methyl ether) (PVME) in water and with terc-buthyl based additives, IPNs of polyacrylamide (PAAm), poly(N -isopropylacrylamide) (PNIPAm), poly(N - vinylcaprolactam) (PVCL) and IPNs and SIPNs of poly(N,N -diethylacrylamide) (PDEAAm) were investigated by the methods of nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), optical microscopy (OM) and swelling experiments. The effect of polymer concentration and presence of additives on the dynamics during the phase separation as well as interactions between the water and the polymer in aqueous solutions of PVME and PVME/additives were established. The increasing content of hydrophilic PAAm component in SIPNs and IPNs shifts the transition toward...
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Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems
Radecki, Marek ; Hanyková, Lenka (advisor) ; Matějka, Libor (referee) ; Kronek, Juraj (referee)
Title: Spectroscopic Study of the Dynamical Behavior and Interactions in Supramolecular and Macromolecular Systems Author: Marek Radecki Department: Department of Macromolecular Physics Supervisor: Doc. RNDr. Lenka Hanyková, Dr., Department of Macromolecular Physics Abstract: In this thesis, the temperature-induced phase transition in liner polymer solutins and hydrogels of semi-interpenetrating (SIPNs) and interpenetrating (IPNs) polymer networks was studied with respect to various composition, network architecture and procedure. Thermoresponsive linear polymers based on poly(vinyl methyl ether) (PVME) in water and with terc-buthyl based additives, IPNs of polyacrylamide (PAAm), poly(N -isopropylacrylamide) (PNIPAm), poly(N - vinylcaprolactam) (PVCL) and IPNs and SIPNs of poly(N,N -diethylacrylamide) (PDEAAm) were investigated by the methods of nuclear magnetic resonance spectroscopy (NMR), differential scanning calorimetry (DSC), optical microscopy (OM) and swelling experiments. The effect of polymer concentration and presence of additives on the dynamics during the phase separation as well as interactions between the water and the polymer in aqueous solutions of PVME and PVME/additives were established. The increasing content of hydrophilic PAAm component in SIPNs and IPNs shifts the transition toward...
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Interactions in solutions and gels of stimuli-responsive polymer systems investigated by NMR spectroscopy
Konefał, Rafał ; Spěváček, Jiří (advisor) ; Hrabal, Richard (referee) ; Štěpánek, Miroslav (referee)
Stimuli-responsive (stimuli-sensitive, intelligent, or smart) polymers are polymer materials which, after small external stimuli, evidently change their physical or chemical properties. Smart polymers can be classified according stimuli they respond to such as: temperature changes, mechanical stress, light irradiation, ultrasonic treatment, application of external magnetic as well as electric field, changes of pH, ionic strength, addition of the chemical agents and presence of biomolecules and bioactive molecules. Stimuli-responsive synthetic polymer systems has attracted considerable attention due to wide range of applications, i.e. controlled drug delivery and release systems, diagnostics, tissue engineering and 'smart' optical systems, as well as biosensors, microelectromechanical systems, coatings, and textiles. Among the types of stimuli for this dissertation temperature, pH and reactive oxygen species (ROS) responsive polymer systems were studied. In case of thermoresponsive polymers, when polymer chains are molecularly dissolved in a good solvent, changes (increasing or decreasing) of temperature result in insolubility (globular nanoparticles formation) of polymer chains, called temperature induced phase-separation. pH responsive polymers change properties such as: solubility, volume (gels),...
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Temperature-sensitive hydrogels
Šestáková, Eliška ; Hanyková, Lenka (advisor) ; Kouřilová, Hana (referee)
Hydrogely jsou měkké látky složené z polymerních sítí nabotnalých ve vodě. Některé z nich při změně teploty reagují skokovou změnou objemu. Tento fázový přechod je označován jako kolaps a odpovídá konformační změně, při které polymerní řetězce přechází z konformace klubka do konformace globule. Vlastnostmi se hydrogely podobají živým tkáním (chrupavkám, šlachám a sval·m), nejen proto jsou perspektivními materiály ohledně aplikací v biotechnologiích a farmacii. Tato práce se zabývá studiem kolapsu v hydrogelech tvořenými jednoduchými a dvojitými sítěmi (speciální případ dvou interpenetrujících polymerních sítí). Připravené vzorky (PNIPAAm, PNNDEAAm, PAMPS, PAAm a odpovídající dvojité sítě s PAAm jako druhou složkou) byly zkoumány pomocí botnacích, DSC a NMR experiment·. Botnací experimenty prokázaly, že dvojité sítě vykazují větší míru nabotnání a také vyšší kritickou teplotu než příslušné sítě jednoduché. Pomocí NMR a DSC experiment· byla určena entalpie kolapsu. Bylo zjištěno, že na signálech NMR se podílí jen část polymerních jednotek teplotně citlivého hydrogelu kv·li velké hustotě sesí'ování. 1
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Temperature-sensitive functional molecules
Spasovová, Monika ; Hanyková, Lenka (advisor) ; Starovoytova, Larisa (referee)
The object of our study is a phase separation of porphyrin derivative PNIPAm-TPP. This molecule combines the properties of temperature-responsive polymers with those of well- defined small organic molecules. It is one of the few small organic molecule which shows temperature responsive behavior. We studied its phase separation using high resolution NMR spectroscopy and optical microscope. We applied Flory-Huggins theory to experimental data gained from VT (variable temperature) experiments and we obtained a phase diagram with spinodal and binodal curve. We also obtained LCST (lower critical solution temperature) of the solution and its critical concentration.
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PFM and Raman spectroscopy of selected dielectric materials
Borodavka, Fedir ; Gregora, Ivan (advisor) ; Baumruk, Vladimír (referee) ; Hehlen, Bernard (referee)
Title: PFM and Raman spectroscopy of selected dielectric materials Author: Fedir Borodavka Institute: Department of Dielectrics, Institute of Physics of the Academy of Sciences, Na Slovance 2, 182 21, Prague 8, Czech Republic Supervisor: Ing. Ivan Gregora, CSc. Training institute: Department of Dielectrics, Institute of Physics of the Academy of Sciences, Na Slovance 2, 182 21, Prague 8, Czech Republic Consultants: RNDr. Stanislav Kamba, CSc. and RNDr. Vladimír Vorlíček, CSc. Abstract: The thesis is devoted to a detailed investigation of dielectric materials using Raman spectroscopy and PFM microscopy techniques. Phonon properties of a newly synthesized guanylurea(1+) hydrogen phosphite single crystals have been studied. A tentative assignment of the observed Raman peaks has been done and the sets of A′ MIX, A′ TO and A′′ TO mode frequencies have been determined. Phonon behaviour of BiMnO3 ceramics, obtained from Raman spectra, has been char- acterized. After comparing the factor group analysis with the Raman spectra it has been concluded that the material has a centrosymmetric C2/c structure and is not ferroelectric. Lattice modes of the complex La1/2Na1/2TiO3 single crystal have been investigated. We have numerically analysed the intensity behaviour of the sharp peak at 455 cm−1 on heating and...
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Laser spectroscopy of materials for spintronics
Brajer, Martin ; Němec, Petr (advisor) ; Jakubisová, Eva (referee)
In these diploma thesis magnetically ordered materials are studied with the prospect of their application in spintronics. Specifically, we investigated metallic alloy FeRh, which undergoes a magnetic phase transition from antife- romagnetic phase to feromagnetic one around 100◦ C. This phenomenon can be readily used in memory devices. Laser spectroscopy is used as a nondestructive method without need of any electrical contacts. Magnetic properties of FeRh are studied by magnetooptical effects including quadratic magnetic linear dichroism. The measured polarization rotations are of the order of miliradians, therefore, the detection is realized by an optical bridge. At first, we concentrated on discrimina- ting of various magnetooptical effects from each other. The second part is focused on the phase transition induced by different means. Firstly, by heating the whole sample, secondly by illuminating the sample locally by continuous laser.
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Tunable materials and structures for terahertz spectral range
Skoromets, Volodymyr ; Kužel, Petr (advisor) ; Hlídek, Pavel (referee) ; Pashkin, Alexei (referee)
This thesis is devoted to an experimental study of dielectric properties of incipient fer- roelectrics. The terahertz time-domain spectroscopy was used to investigate the complex permittivity spectra in both single crystals and various strained thin film structures versus temperature and applied electric bias. Namely, it allowed characterizing the ferroelectric soft-mode dynamics and its coupling to a central mode. An electric-field tunability of bulk single crystals of SrTiO3 was determined up to room temperature for the first time. The phenomenon is governed by soft-mode stiffening under applied field. As an application we proposed and characterized a tunable one-dimensional photonic structure with a thin SrTiO3 plate inserted as a defect layer. The importance of the soft-mode dynamics was stressed also in the study of bulk high density KTaO3 ceramics. A systematic study was performed of a KTaO3 thin film and especially of a set of strained multilayers consisting of SrTiO3/DyScO3 bilayers grown on DyScO3 substrate. Strain-induced ferroelectric transition was observed in these films governed by the soft mode coupled to a lower-frequency relaxation. A general model was developed describing the whole family of the studied samples. Effect of the composition stoichiometry of SrTiO3 films grown on DyScO3 was...
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Matematické modelování růstu krystalů
Blechta, Jan ; Hron, Jaroslav (advisor) ; Souček, Ondřej (referee)
We present a numerical model of Bridgman crystal growth. Pseudo-incompressibility constraint is used to handle jumps in density during phase change. ALE formulation is employed to account for moving parts of the system. Field equations and movement of material interfaces are decoupled in fractional step manner. Naviér-Stokes problem is extended to solid phase where no flow is enforced by Darcy-like forcing. Latent heat of phase change is added to effective heat capacity as approximate Dirac-$\delta$. Backward Euler discretization in space and P2/P1/P1 in space are used. Transient and stationary solutions are being found and compared to temperatures measured directly inside a steady system. Influence of pull-rates on growth process and shape of phase interface are being examined. Powered by TCPDF (www.tcpdf.org)
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Quantal and thermal phase transitions in atomic nuclei
Dvořák, Martin ; Cejnar, Pavel (advisor) ; Knapp, František (referee)
In this bachelor work phase transitions in atomic nuclei are studied. The main attention is paid to quantal phase transitions between nuclear ground states of different symmetry. First, the interacting boson model in its simplest version, IBM-1, is introduced. The correspondence between the IBM and the geometric model of nuclei is indicated and possible shapes of the nucleus in the ground state are introduced. In the next step, critical and degenerated critical points of the potential derived from the IBM-1 are investigated in detail, especially their dependence on parameter values of the potential. Degenerated critical points are classified using the catastrophe theory. The special values of potential parameters are found for which phase transitions of the first and second order occur. Finally, the possibility of substitution of the potential by canonical catastrophic functions in a vicinity of degenerated critical points is discussed.
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