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Electrospinning of ceramic fibers
Nemčovský, Jakub ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
This diploma thesis focuses on the fabrication of ceramic fibres by electrospinning. The theoretical part of the thesis summarizes the currently available information regarding ceramic fibres, their properties, applications and fabrication. The theoretical part also describes the process of electrospinning as one of the most frequently used methods of nanofibre fabrication, as well as the parametres influencing this process. The experimental part is aimed at the fabrication of ceramic fibres based on titania, pure non-doped zirconia and yttria-doped zirconia by electrospinning and at the characterization of thus fabricated fibres. Ceramic precursors based on propoxide and polyvinylpyrrolidone were subjected to electrospinning. The experimental part of this diploma thesis also describes the influence of precursor composition, process conditions and calcination temperature on the morphology and phase composition of the fibres. Precursors were characterized by viscosity measurements. Thermogravimetric analysis (TGA), Röntgen analysis (RTG) and scanning electron microscopy (SEM) were used to describe the fibres. By performing electrospinning of precursors based on titanium propoxide and subsequent calcination at 500-1300 °C, TiO2 fibres with thickness of 100-2500 nm were fabricated. The phase composition changed with calcination temperature from 500 °C from anatase phase through rutile blend to pure rutile at 900 °C. By performing electrospinning of precursors based on zirconium propoxide and subsequent calcination at 550-1100 °C, 0 – 8 mol% Y2O3 doped ZrO2 fibres with thickness of 50-1000 nm were fabricated. An analysis of fibres based on non-doped ZrO2, calcined at 550 °C showed a composition of predominantly monoclinic phase. An analysis of 3 or 8 mol% Y2O3 doped ZrO2 fibres calcined at 900 °C showed a composition of predominantly tetragonal phase or purely cubic phase, respectively. With the increasing calcination temperature, the morphology of the fibres changed from porous nanostructure to chain-like non-porous structure consisting of micrometer grains of TiO2 or ZrO2. The ZrO2 fibres calcined at 700 °C remained flexible as well as the spun ones, while their fragility increased with the increase in calcination temperature.
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Preparation of thin wall ceramic hollow fibers by dip-coating
Gockert, Radek ; Maca, Karel (referee) ; Salamon, David (advisor)
Tato diplomová práce se zabývá výrobou ultratenkých keramických dutých vláken pomocí metody povlakování namáčením. Příprava keramických dutých vláken je v současnosti limitována rozměrem vnějšího a vnitřního průměru. Aplikace metody povlakování namáčením pro přípravu ultratenkých dutých je nový a technologicky náročný proces vyžadující volbu vhodné šablony a zároveň zvládnutí kontroly parametrů povlakování. Základními zvolenými materiály s vysokým aplikačním potenciálem jsou hydroxyapatit a oxid titaničitý. Samonosná dutá vlákna s tloušťkou stěny pod 1 m byla úspěšně připravena z obou materiálů. Dále byl také popsán proces povlakování namáčením obětovaných šablon. Tato metoda je unikátní, protože umožňuje produkci ultratenkých keramických dutých vláken s vnitřním průměrem pod 100 m a tloušťkou stěny pod 1 m.
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Neural bioceramic scaffold prepared by freeze-casting
Vojníková, Michaela ; Pejchalová, Lucie (referee) ; Salamon, David (advisor)
Pre regeneráciu a rast poranených nervových vlákien bolo preskúmaných mnoho postupov, no výsledný rast axónov je často náhodný až dezorganizovaný a odráža sa na zložitejšom zotavovaní pacienta. V tejto práci boli vyrobené nové skafoldy s mikroštruktúrnymi a mechanickými vlastnosťami nervového skafoldu pomocou metódy freeze-casting. Konkrétne boli vyrobené biokeramické skafoldy na báze fosforečnanov vápenatých, oxidu titaničitého alebo oxidu zirkoničitého. Pomocou kontrolovaného rastu ľadu v jednom smere bola pripravená orientovaná mikroštruktúra. Pozorovanie pomocou skenovacej elektrónovej mikroskopie potvrdilo lineárne orientované póry (lamelárny systém), v ktorých priemerná veľkosť pórov klesala so zvyšujúcou sa rýchlosťou mrazenia. Skafoldy pripravené pomocou mrazenia v tekutom dusíku vykazovali vynikajúce mechanické vlastnosti, kde pevnosť v ohybe bola získaná v rozmedzí 10–17 MPa. Tie isté skafoldy mali vzdialenosť medzilamelamelárnych priestorov 10–30 µm, ktorých parametre sú vhodné pre nervové skafoldy. Biokompatibilita bola vyhodnotená pomocou Schwannových buniek in vitro, kde bola pozorovaná adhézia a rast v lamelárnom smere. Cytotoxické testy odhalili negatívny vplyv vyššej koncentrácie vápnika na prežitie Schwannových buniek. Pripravené skafoldy mali schopnosť tvorby apatitu na povrchu v podobe embryonálnych a nukleačných centier a apatitu samotného. Skafoldy na báze fosforečnanov vápenatých a oxidu titaničitého vykazovali sľubné regeneračné vlastnosti, konkrétne adhéziu a rast prostredníctvom pórovitej štruktúry a taktiež vynikajúce mechanické vlastnosti.
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Application of Electronic Continuum Correction to Molecular Simulations of Nano/Bio Interfaces
BIRIUKOV, Denys
Nowadays it is almost impossible to imagine our life without nanotechnologies. They are present in smartphones and many other gadgets we use every day, while advanced nanoparticle-based devises are currently indispensable in medicine, engineering, and science. In the case of biomedical applications, the knowledge how a specific nanomaterial behaves and changes its properties in complex physiological medium is essential to guarantee the accomplishment of all specific goals facing a scientist or engineer. Some of physical and chemical processes occurring when a nanodevice enters biological environment are yet very difficult to fully detail without accurate computer simulations, so special attention needs to be focused on theoretical studies of nano-bio interactions. In this thesis, molecular simulations were used to investigate the interactions between different nanomaterials (titanium dioxide, silicon dioxide, and gold) and aqueous solutions, which contain ions, organic molecules, and amino acids. The importance of this scope and particularly selected for this study materials and compounds is given in Introduction. To model nano/bio interfaces, we adopted and integrated recent theoretical approaches, which together with basic principles of molecular simulations are described in Methods. Obtained results are divided in four parts and address several important issues that are vital in deciphering molecular mechanisms, through which nanoparticles identify and bind various biomolecules. The simulation data are thoroughly discussed, compared to experiments, and used to explain some of experimental observations. Additionally, outcomes of this thesis serve as a springboard for further theoretical studies aimed to advance our understanding of nano-bio interactions.
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Neural bioceramic scaffold prepared by freeze-casting
Vojníková, Michaela ; Pejchalová, Lucie (referee) ; Salamon, David (advisor)
Pre regeneráciu a rast poranených nervových vlákien bolo preskúmaných mnoho postupov, no výsledný rast axónov je často náhodný až dezorganizovaný a odráža sa na zložitejšom zotavovaní pacienta. V tejto práci boli vyrobené nové skafoldy s mikroštruktúrnymi a mechanickými vlastnosťami nervového skafoldu pomocou metódy freeze-casting. Konkrétne boli vyrobené biokeramické skafoldy na báze fosforečnanov vápenatých, oxidu titaničitého alebo oxidu zirkoničitého. Pomocou kontrolovaného rastu ľadu v jednom smere bola pripravená orientovaná mikroštruktúra. Pozorovanie pomocou skenovacej elektrónovej mikroskopie potvrdilo lineárne orientované póry (lamelárny systém), v ktorých priemerná veľkosť pórov klesala so zvyšujúcou sa rýchlosťou mrazenia. Skafoldy pripravené pomocou mrazenia v tekutom dusíku vykazovali vynikajúce mechanické vlastnosti, kde pevnosť v ohybe bola získaná v rozmedzí 10–17 MPa. Tie isté skafoldy mali vzdialenosť medzilamelamelárnych priestorov 10–30 µm, ktorých parametre sú vhodné pre nervové skafoldy. Biokompatibilita bola vyhodnotená pomocou Schwannových buniek in vitro, kde bola pozorovaná adhézia a rast v lamelárnom smere. Cytotoxické testy odhalili negatívny vplyv vyššej koncentrácie vápnika na prežitie Schwannových buniek. Pripravené skafoldy mali schopnosť tvorby apatitu na povrchu v podobe embryonálnych a nukleačných centier a apatitu samotného. Skafoldy na báze fosforečnanov vápenatých a oxidu titaničitého vykazovali sľubné regeneračné vlastnosti, konkrétne adhéziu a rast prostredníctvom pórovitej štruktúry a taktiež vynikajúce mechanické vlastnosti.
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Suspension plasma spraying of sub-stoichiometric titania by hybrid water/argon stabilized plasma torch
Mušálek, Radek ; Ctibor, Pavel ; Medřický, Jan ; Tesař, Tomáš ; Kotlan, Jiří ; Lukáč, František
In this study, suspension plasma spraying of sub-stoichiometric titania was attempted using hybrid water/argon stabilized plasma torch (WSP-H). Porous coatings with fine cauliflower-like columnar microstructure were successfully deposited in two separate experiments with different power levels of the plasma torch. In both cases, high solid-load content (40 wt. %) of the water-based suspension resulted in considerable coating thickness increase per deposition cycle. Coating annealing and partial remelting of the surface asperities were also achieved by additional pass of plasma torch in front of the coating surface. According to X-ray diffraction, all coatings consisted dominantly of rutile phase. Detailed microscopic observation of the as-sprayed and annealed deposits showed that the local coloration of the coating (ranging from dark blue to beige) was driven by the local overheating of the rough coating surface which could also promote the oxygen intake. Moreover, sample annealing was also observed to increase the sample reflectivity as observed by UV-VIS-NIR scanning spectrophotometry
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Electrospinning of ceramic fibers
Nemčovský, Jakub ; Kaštyl, Jaroslav (referee) ; Částková, Klára (advisor)
This diploma thesis focuses on the fabrication of ceramic fibres by electrospinning. The theoretical part of the thesis summarizes the currently available information regarding ceramic fibres, their properties, applications and fabrication. The theoretical part also describes the process of electrospinning as one of the most frequently used methods of nanofibre fabrication, as well as the parametres influencing this process. The experimental part is aimed at the fabrication of ceramic fibres based on titania, pure non-doped zirconia and yttria-doped zirconia by electrospinning and at the characterization of thus fabricated fibres. Ceramic precursors based on propoxide and polyvinylpyrrolidone were subjected to electrospinning. The experimental part of this diploma thesis also describes the influence of precursor composition, process conditions and calcination temperature on the morphology and phase composition of the fibres. Precursors were characterized by viscosity measurements. Thermogravimetric analysis (TGA), Röntgen analysis (RTG) and scanning electron microscopy (SEM) were used to describe the fibres. By performing electrospinning of precursors based on titanium propoxide and subsequent calcination at 500-1300 °C, TiO2 fibres with thickness of 100-2500 nm were fabricated. The phase composition changed with calcination temperature from 500 °C from anatase phase through rutile blend to pure rutile at 900 °C. By performing electrospinning of precursors based on zirconium propoxide and subsequent calcination at 550-1100 °C, 0 – 8 mol% Y2O3 doped ZrO2 fibres with thickness of 50-1000 nm were fabricated. An analysis of fibres based on non-doped ZrO2, calcined at 550 °C showed a composition of predominantly monoclinic phase. An analysis of 3 or 8 mol% Y2O3 doped ZrO2 fibres calcined at 900 °C showed a composition of predominantly tetragonal phase or purely cubic phase, respectively. With the increasing calcination temperature, the morphology of the fibres changed from porous nanostructure to chain-like non-porous structure consisting of micrometer grains of TiO2 or ZrO2. The ZrO2 fibres calcined at 700 °C remained flexible as well as the spun ones, while their fragility increased with the increase in calcination temperature.
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Preparation of thin wall ceramic hollow fibers by dip-coating
Gockert, Radek ; Maca, Karel (referee) ; Salamon, David (advisor)
Tato diplomová práce se zabývá výrobou ultratenkých keramických dutých vláken pomocí metody povlakování namáčením. Příprava keramických dutých vláken je v současnosti limitována rozměrem vnějšího a vnitřního průměru. Aplikace metody povlakování namáčením pro přípravu ultratenkých dutých je nový a technologicky náročný proces vyžadující volbu vhodné šablony a zároveň zvládnutí kontroly parametrů povlakování. Základními zvolenými materiály s vysokým aplikačním potenciálem jsou hydroxyapatit a oxid titaničitý. Samonosná dutá vlákna s tloušťkou stěny pod 1 m byla úspěšně připravena z obou materiálů. Dále byl také popsán proces povlakování namáčením obětovaných šablon. Tato metoda je unikátní, protože umožňuje produkci ultratenkých keramických dutých vláken s vnitřním průměrem pod 100 m a tloušťkou stěny pod 1 m.
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Deposition of Titania from Solution by Hybrid Water-Stabilized Plasma Torch
Mušálek, Radek ; Medřický, Jan ; Tesař, Tomáš ; Kotlan, Jiří ; Lukáč, František
Thermal spraying with liquid feedstock presents a novel route for deposition of functional coatings. In this study, possibility of preparation of titania coatings from solution by hybrid water stabilized plasma torch is presented. Coatings were prepared from solution of titanium isopropoxide Ti[OCH(CH3)2]4 in anhydrous ethanol. Fragmentation of feedstock stream in the plasma jet was monitored by shadowgraphy. Deposition was carried out on steel samples mounted to the cooled rotating carousel. Cross-sectional images from SEM microscope showed successful formation of the deposit with dual morphology consisting of fine feather-like features combined with bigger droplets. X-ray diffraction revealed formation of nanometric rutile crystallites.
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