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Polyvinyl alcohol hydrogels with gradient structure in crosslinking density
Ščotková, Romana ; Kalina, Michal (referee) ; Smilek, Jiří (advisor)
The presented thesis introduce one of the many possibilities for the physical preparation of PVA hydrogels with a gradient in the crosslinking density. Based on the research conducted, the main focus of which was the preparation methods of gradient hydrogels and the characterization of their properties, a cyclic freezing and thawing method was selected and optimized with a focus on the selected preparation parameters. The next step was to perform pilot experiments leading to the confirmation and characterization of the resulting gradient structure by selected instrumental techniques such as rheology, scanning electron microscopy or a method based on monitoring the loss of dispersion during drying of the samples. In addition to the confirmation of the gradient structure, one of the parameters studied was the effect of the addition of polysaccharide on the resulting mechanical properties. Gradient hydrogels with different molecular weights or biopolymer additions were compared in the second part of the experimental work based on diffusion experiments using methylene blue. At the end of the work, all the results obtained were discussed and additional measurements were proposed for a deeper understanding of the subject.
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Corelation of transport and viscoelastic properties of hydrogels with diffusion gradient
Ščotková, Romana ; Sedláček, Petr (referee) ; Smilek, Jiří (advisor)
The aim of the presented bachelor thesis was to prepare hydrogels with diffusion gradient and to demonstrate the gradient structure of hydrogels in terms of viscoelastic and transport properties. With regard to potential biomedical applications, the cationic polysaccharide chitosan was selected for the preparation, especially for its antimicrobial and biocompatible properties. The resulting gradient hydrogels were subsequently characterized by oscillation tests to observe the differences using different concentrations and molecular weights of chitosan, crosslinking agent concentrations, dispersion environments for chitosan dissolution, and different gel crosslinking times. The samples were also subjected to drying experiments to confirm the gradient structure formed. The ability of the hydrogels to transport the active species was confirmed by visually evaluating the permeation of the anionic dye (bromothymol blue) during the gelation process. From the results obtained during the experimental part of the bachelor thesis it can be concluded that the viscoelastic properties of hydrogels can be modified by changing selected parameters during the preparation itself. It was also confirmed the assumption that with better mechanical properties of hydrogels there is a deterioration of transport properties. By controlled diffusion method, it was possible to prepare a hydrogel with a gradual gradient of crosslinking density, thus modifying the viscoelastic and transport properties.
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Corelation of transport and viscoelastic properties of hydrogels with diffusion gradient
Ščotková, Romana ; Sedláček, Petr (referee) ; Smilek, Jiří (advisor)
The aim of the presented bachelor thesis was to prepare hydrogels with diffusion gradient and to demonstrate the gradient structure of hydrogels in terms of viscoelastic and transport properties. With regard to potential biomedical applications, the cationic polysaccharide chitosan was selected for the preparation, especially for its antimicrobial and biocompatible properties. The resulting gradient hydrogels were subsequently characterized by oscillation tests to observe the differences using different concentrations and molecular weights of chitosan, crosslinking agent concentrations, dispersion environments for chitosan dissolution, and different gel crosslinking times. The samples were also subjected to drying experiments to confirm the gradient structure formed. The ability of the hydrogels to transport the active species was confirmed by visually evaluating the permeation of the anionic dye (bromothymol blue) during the gelation process. From the results obtained during the experimental part of the bachelor thesis it can be concluded that the viscoelastic properties of hydrogels can be modified by changing selected parameters during the preparation itself. It was also confirmed the assumption that with better mechanical properties of hydrogels there is a deterioration of transport properties. By controlled diffusion method, it was possible to prepare a hydrogel with a gradual gradient of crosslinking density, thus modifying the viscoelastic and transport properties.
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