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Molecular dynamics study of admixture influence on structural properties and stability of fatty acid Langmuir monolayers
Kubániová, Denisa ; Roeselová, Martina (advisor)
Using the classical molecular dynamics simulations, the interfacial partitioning of selected aromatic species, namely benzoic acid and neutral and zwitterionic form of L-phenylalanine, was studied in the three slab systems: a) aqueous organics solution, b) palmitic acid monolayer in tilted condensed phase at aqueous organics solution and c) palmitic acid monolayer in tilted condensed - 2D gas phase coexistence at aqueous organics solution. The surface activity and the tendency to aggregate in particular at the air- aqueous and palmitic acid-aqueous interface was confirmed for all of the investigated aromatic species. The results of the simulation performed for the system of palmitic acid monolayer at benzoic acid solution were compared with the literature results of a similar simulation that employed a different parametrization. The comparison showed that the behaviour of the aromatic species at the fatty acid monolayer-aqueous interface strongly depends on the force field. The structural properties of the palmitic acid Langmuir monolayers were evaluated by means of the chain tilt angle and the headgroup region dihedral angle distributions analysis depending on the surface film density and the adsorbed aromatic species. The simulations mimicking the isothermal compression of the mixed monolayer in the...
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Molecular dynamics study of admixture influence on structural properties and stability of fatty acid Langmuir monolayers
Kubániová, Denisa ; Roeselová, Martina (advisor)
Using the classical molecular dynamics simulations, the interfacial partitioning of selected aromatic species, namely benzoic acid and neutral and zwitterionic form of L-phenylalanine, was studied in the three slab systems: a) aqueous organics solution, b) palmitic acid monolayer in tilted condensed phase at aqueous organics solution and c) palmitic acid monolayer in tilted condensed - 2D gas phase coexistence at aqueous organics solution. The surface activity and the tendency to aggregate in particular at the air- aqueous and palmitic acid-aqueous interface was confirmed for all of the investigated aromatic species. The results of the simulation performed for the system of palmitic acid monolayer at benzoic acid solution were compared with the literature results of a similar simulation that employed a different parametrization. The comparison showed that the behaviour of the aromatic species at the fatty acid monolayer-aqueous interface strongly depends on the force field. The structural properties of the palmitic acid Langmuir monolayers were evaluated by means of the chain tilt angle and the headgroup region dihedral angle distributions analysis depending on the surface film density and the adsorbed aromatic species. The simulations mimicking the isothermal compression of the mixed monolayer in the...
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Nanoparticles formed by complexes of copolymers with low-molar-mass compounds
Vojtová, Jana ; Štěpánek, Miroslav (advisor) ; Filippov, Sergej (referee) ; Hoffmann, Ingo (referee)
This thesis is focused on mixed systems of various copolymers (double hydrophilic block and gradient polyelectrolytes, hydrophobic graft copolymers) and low-molar-mass compounds (sodium dodecyl sulfate as a representative of a ionic surfactant or superparamagnetic iron oxides in the form of nanocrystals). The electrostatic and hydrophobic interactions in the studied systems in aqueous solutions leading to aggregation behavior and to the formation of co-assembled nanoparticles were investigated by combination of scattering and microscopy techniques, including light, X-ray and neutron scattering, electron microscopy and atomic force microscopy. Powered by TCPDF (www.tcpdf.org)
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Self-Assembly in Mixture of Surfactants and Stimuli-Responsive Polymers with Complex Architecture
Bogomolova, Anna ; Filippov, Sergej (advisor) ; Štěpánek, Miroslav (referee) ; Hanyková, Lenka (referee)
Title: Self-assembly in mixture of surfactants and stimuli-responsive polymers with complex architecture Author: Anna Bogomolova Department: Physical and Macromolecular Chemistry Supervisor: PhD. Sergey K. Filippov, IMC AS CR, v.v.i. Supervisor's e-mail address: filippov@imc.cas.cz Abstract: The issue of construction of complex multi-block copolymers is currently one of the most researched areas. It became a logic consequence of the continuous development in polymer chemistry. Nowadays, a great interest is attracted to multi- responsive block copolymers. As a rule, they consist of hydrophilic, hydrophobic and responsive blocks. That responsive block can be either thermo-sensitive or pH-sensitive as well as sensitive to some other external stimuli. In the present work, we will try to cover topic of stimuli-responsive block copolymers and their interactions with different types of surfactants. Understanding of polymer/surfactant interactions can be a crucial step for future modeling of drug/polymer or protein(DNA)/surfactant interactions. There is a great interest in the investigation of polymer-surfactant interactions. However, while the homopolymer-surfactant interactions are characterized well enough, the same interactions for block copolymers are poorly described. The main development in the latter topic...
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Preparation and characterization of nanoparticles formed by polymer-surfactant complexes
Dvořák, Filip ; Štěpánek, Miroslav (advisor) ; Netopilík, Miloš (referee)
In this work, copolymers of celulose-g-polystyrene (cel-PS) and celulose-g- poly(methylmetacrylate) (cel-PMMA) were characterized using static and dynamic light scattering, transmission electron microscopy and atomic force microscopy. Preparation of nanoparticles of these hydrophobic copolymers in aqueous solution was further studied, by means of precipitation from dioxane solutions using water with added low-molar-mass surfactants sodium dodecylsulfate (SDS) and dodecyltrimethylammonium bromide (DTMAB). It was shown that the ability of the surfactants to stabilize polymer nanoparticles is driven not only by the hydrophobic effect, but it depends also on specific interactions of the polar group of the surfactant with the surface of the nanoparticles. On the basis of the finding that the efficiency of stabilization of cel-PS copolymers is much higher than in case of linear PS, it can be concluded, that the branched structure of copolymers is favorable for the formation of hydrofobically stabilised polymer-surfactant complexes.
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Ecotoxicity of nanomaterials
Viltová, Naďa ; Kočí, Vladimír (advisor) ; Motejlová, Hana (referee)
Recently, nanotechnology has gained a lot of interest and the likelihood of emission of nanomaterials into the enviromment increases as well as the risk of its adverse effects. There is very little information about the behaviour and effects of nanomaterials in the environment, but so far the studies indicate an increasing rate of adverse effects of nanomaterials with decreasing particle size. The aim of this work was to determine the toxicity of nanoparticles of CeO2 of the size of 47,7 nm and 2,1 nm on a green, freshwater algae Desmodesmus subspicatus. Furthermore, the influence of surfactant addition on the toxicity of both substances was evaluated. The results showed that the particle of 2,1 nm showed a higher toxicity than the bigger particles, which is consistent with that was found in the literature. After addition of surfactant, an increase of toxicity was observed increase for both forms
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Studying the effect of the application of inorganic nanofibers in high strength concretes
Sedláček, Daniel ; Hela, Rudolf (referee) ; Bodnárová, Lenka (advisor)
This thesis summarizes the current knowledge of reinforcement of concrete with nanofibers and conducted research on the issue of the use of inorganic nanofibers in ultrahighperformance concrete. Up to now, most researches focuses on the reinforcement using carbon nanotubes and nanofibers and inorganic nanofibers remained in the background of interest. Due to their different chemical properties, is not only a question of their influence on the microstructure and mechanical properties of concrete, but also the preparation of nanofiber suspension which is not explored such as in the case of carbon nanotubes and nanofibres.
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Nanoparticles formed by complexes of copolymers with low-molar-mass compounds
Vojtová, Jana
This thesis is focused on mixed systems of various copolymers (double hydrophilic block and gradient polyelectrolytes, hydrophobic graft copolymers) and low-molar-mass compounds (sodium dodecyl sulfate as a representative of a ionic surfactant or superparamagnetic iron oxides in the form of nanocrystals). The electrostatic and hydrophobic interactions in the studied systems in aqueous solutions leading to aggregation behavior and to the formation of co-assembled nanoparticles were investigated by combination of scattering and microscopy techniques, including light, X-ray and neutron scattering, electron microscopy and atomic force microscopy. Powered by TCPDF (www.tcpdf.org)
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Comicellization of polystyrene-block-poly(acrylic acid) with low-molar-mass surfactants
Paloncýová, Markéta ; Matějíček, Pavel (referee) ; Štěpánek, Miroslav (advisor)
This B.Sc. thesis deals with the study of the effect of low-molar-mass ionic surfactants sodium dodecyl sulfate (SDS) and hexydecyltrimethylammonium bromide (HTAB) on association behavior of the block copolymer polystyrene-b-polyacrylic acid (PS-b-PAA) in alkaline aqueous solutions. Prepared polymeric nanoparticles were characterized by static and dynamic light scattering, transmission electron microscopy and 1 H NMR spectroscopy. It was found that both surfactants interact only with PAA blocks and their presence in the system leads to worsening of the copolymer solubility which manifests itself in the formation of large micellar aggregates and in precipitation of the copolymer-surfactant complexes.
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Castables with Inorganic Nanofibers
Zogata, Stanislav ; Keršnerová,, Lucie (referee) ; Sokolář, Radomír (advisor)
This work deals with the use of inorganic nanofibers in refractory castables. The thesis describes some of the results of previously conducted research on nanofibers. Also description of nanofibres, production and distribution. The experimental part is focused on studying the interaction of Al2O3 and SiO2 nanofibres with aluminate cement. The main subject of investigation is a dispersion of nanofibers using a surfactant and ultrasonication.
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