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Comicellization of polystyrene-block-poly(acrylic acid) with low-molar-mass surfactants
Paloncýová, Markéta ; Štěpánek, Miroslav (advisor) ; Matějíček, Pavel (referee)
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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Counterion condensation on a polyelectrolyte: A fluorescence quenching study
Riedlová, Kamila ; Štěpánek, Miroslav (advisor) ; Humpolíčková, Jana (referee)
In this thesis, we studied the counterion condensation on the polyelectrolyte chain by means of the fluorescence quenching technique, using poly(methacrylic acid) (PMAA) labelled by the naphthyl group either at the end or in the middle of the chain and cesium ions as counterions which act as the fluorescence quencher. Both polymer samples were characterized by dynamic light scattering. The interaction of Cs+ ions with the polyelectrolyte was studied in solvents differing in the dielectric permittivity, using mixtures of water with 1,4-dioxane. The results confirm that fluorescence quenching is enhanced by the counterion condensation and that this process is more pronounced in the case of the naphthyl moiety localized in the middle of the PMAA chain.
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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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Scattering and spectroscopic studies of polyelectrolytes and associating block copolymers
Škvarla, Juraj ; Štěpánek, Miroslav (advisor) ; Špírková, Milena (referee) ; Humpolíčková, Jana (referee)
This dissertation focuses on application of scattering and spectroscopic techniques for studies of self-assembled systems of amphiphiles (both polymeric and low-molar mass) and polyelectrolytes in aqueous solutions. Special attention was paid to optical methods, namely static, dynamic and electrophoretic light scattering and steady-state and time-resolved fluorescence spectroscopy, which were supported by a number of other techniques such as small-angle X-ray scattering or transmission electron microscopy. The dissertation brings new results regarding micellization behavior of perfluorinated surfactants, self-assembly and stability of thermoresponsive amphiphilic block copolymers and counterion condensation on polyelectrolytes in aqueous solution.
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Nanoparticles based on block copolymer complexes with fluorosurfactants
Škvarla, Juraj ; Štěpánek, Miroslav (advisor) ; Netopilík, Miloš (referee)
This thesis deals with (i) complex nanoaggregates of cationic perfluorinated surfactant N-(1,1,2,2- tetrahydroperfluorodecyl)pyridinium chloride and of double hydrophilic block polyanions poly(ethylene oxide)-b-poly(methacrylate) and poly(ethylene oxide)-b-poly((2-sulfamate-3- carboxylate)isoprene), and with (ii) mixed micelles of amphiphilic copolymer poly(ethylene oxide)- b-poly(e-caprolactone) and nonionic perfluorinated fluorosurfactant Zonyl FSN-100. The study was aimed at the characterization of the association behavior of the block copolymer-fluorosurfactant systems in aqueous solutions depending on the amount of the added surfactant, pH of the solvent and the structure of the copolymers.
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Preparation of hybrid nanoparticles based on interaction of block polyelectrolytes with atypical ions
Mesíková, Soňa ; Matějíček, Pavel (advisor) ; Štěpánek, Miroslav (referee)
The Thesis deals with the co-assembly behaviour of cationic diblock copolymers poly(2- vinyl pyridine)-b-poly(ethylene oxide), P2VP-b-PEO, and poly(ethylene oxide)-b-poly(2- (N, N, N′, N′-tetramethyl guanidinium) ethyl acrylate), PEO-b-PGEA, with closo- dodecaborate anion, [B12H12]2- , in aqueous solutions. Formation of stable PEO-b- PGEA/[B12H12] nanoparticles was investigated by static and dynamic light scattering and 1 H NMR spectroscopy, and they were visualized as spherical nanoparticles by cryo- TEM imaging. According to the NMR results, both studied diblock copolymers form core- corona micelles with dodecaborate. The micellar molar mass and the aggregation number of PEO-b-PGEA/[B12H12] micelles were obtained in water and 0.156 M NaCl solution by standard Zimm method. For this, refractive index increment was evaluated by refractometer. The studied nanoparticles are promising for the boron delivery in medicine.
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Influence of nanoparticles and polymers on the amyloid fibril formation
Holubová, Monika ; Štěpánek, Petr (advisor) ; Štěpánek, Miroslav (referee) ; Nardin, Corrine (referee)
The thesis deals with the testing of amyloidogenicity of various carbon nanoparticles and polymers. The first part of the thesis provides the theoretical background of amyloidoses, a group of diseases in which proteins are stored in the insoluble form of amyloid. In addition, the theoretical part also deals with a general overview of nanomaterials and the most important methods. Several types of nanomaterials were tested within the thesis, so the part Results and Discussion was divided into two subchapters: 1) Carbon nanospecies and amyloid fibril formation, and 2) Polysaccharides, glycogen modifications and amyloid fibril formation. The first subchapter concerns the testing of four types of carbon nanoparticles (single-walled carbon nanotubes (SWNT), fullerenes (C60), carbon quantum dots (CDs) and nanodiamonds (NDs)). These materials were tested on a model system hen egg white lysozyme (HEWL). Using fluorescence measurements and transmission electron microscopy (TEM), the nanoparticles were ranked from the most to the least amyloidogenic as follows: NDs> control> C60> CDs> SWNT. The second subchapter deals with the effect of selected polysaccharides (glycogen (GG), mannan (MAN), phytoglycogen (PG)) and modified GG on amyloid fibril formation. These materials were tested on the HEWL model system,...
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Multidimensional characterization of polyelectrolytes and interpolyelectrolyte complexes in aqueous solutions
Murmiliuk, Anastasiia ; Štěpánek, Miroslav (advisor) ; Šachl, Radek (referee) ; Hoffmann, Ingo (referee)
Multidimensional characterization of polyelectrolytes and interpolyelectrolyte complexes in aqueous solutions Abstract: This PhD thesis is dedicated to the study of polyelectrolytes and their self-assembly in aqueous solutions. The morphology and ionization state of individual polymer chains were investigated as well as their co-assembly with oppositely charged species. First, the charge regulation of short and long weak polyelectrolytes in aqueous solution was investigated to deeper understand their pH-responsive properties. The changes of ionization degree and charge of oligopeptides composed of 5 amino acids with acid side-chains and 5 with basic side chains were followed upon varying the pH in order to reveal the effect of interactions between the like-charged and oppositely charged groups. It was shown that intra-molecular electrostatic interactions and conformational flexibility caused the suppression of the total charge and enhancement of ionization of the peptides. To get an insight into the distribution of local H+ concentration in the proximity of a polyelectrolyte chain, a modified polyelectrolyte structure was used with a fluorescent pH- indicator, covalently attached at the end of the chain. Ionization of the pH-responsive fluorophore revealed its effective pK which was compared with the local...
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