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Biomedical applications of polycaprolactone nanofibrous mats
Dvořák, Pavel ; Přibyl,, Jan (referee) ; Zajíčková, Lenka (advisor)
The diploma thesis deals with the treatment of polycaprolactone (PCL) nanofibers. PCL fibers were subjected to the deposition of plasma amine polymers in a low pressure pulsed radiofrequency capacitively coupled discharge using cyclopropylamine monomer (CPA). Collagen as an extracellular matrix (ECM) protein was immobilized and cell proliferation on the modified nanofiber surface was monitored. Untreated PCL fibers were also subjected to the deposition of an antibacterial copper layer, and the fibers were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive spectroscopy (EDX).
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Piezoelectric nanofiber materials for wearable electronics
Frolíková, Štěpánka ; Škarvada, Pavel (referee) ; Macků, Robert (advisor)
This thesis deals with the influence of production parameters on the morphology of PVDF nanofibers produced by electrospinning. Nanofibers are generally a widely used material, nanofibers are generally a widely used material, they can also have piezoelectric properties, which gives them a specific spectrum of use, eg in biosensors. The production of nanofibers was realized by electrospinning. A scanning electron microscope was used to examine the morphology and surface properties. The aim of this thesis is to compare the properties of PVDF nanofibers produced under different settings of production parameters.
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Characterization of PVDF material in nanoscale resolution
Pisarenko, Tatiana ; Dallaev, Rashid (referee) ; Sobola, Dinara (advisor)
Tato práce se zabývá charakterizací nanovláken na bázi polyvinylidenfluoridu. Zaměření práce je na piezoelektrické vlastnosti vlákna, které jsou studovány metodou piezoelektrické silové mikroskopie. Takto byly měřeny dva typy odlišných vzorků, které se lišily v parametrech výroby. Odlišnosti vláken v jejich fázovém složení byly také zkoumány za využití Ramanovy spektroskopie a infračervené spektroskopie s Fourierovou transformací. Chemická analýza povrchu a jeho stavu proběhla pomocí rentgenové fotoelektronové spektroskopie. Různé uspořádání nanovláken spolu s jejich průřezem bylo pozorováno rastrovacím elektronovým mikroskopem za využití fokusovaného iontového svazku. Rovněž byla zkoumána smáčivost a kontaktní úhel povrchu vzorků s demineralizovanou vodou. Bylo zjištěno, že vyšší rychlost otáček válce během procesu elektrostatického zvlákňování má velmi významný vliv na jejich uspořádání a tím i na parametry ovlivňující tvorbu piezoelektrického jevu a dalších materiálových vlastností.
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Electrospun fibers based on PVDF and nylon
Černohorský, Petr ; Sobola, Dinara (referee) ; Papež, Nikola (advisor)
Polymer nanofibers used for the construction of triboelectric nanogenerator (TENG) and piezoelectric nanogenerator (PENG) are new and promising technologies for energy recovery. Thanks to the generation of electrical energy based on mechanical movement (deformation), these fibers can find application in the field of self-powered electronic devices. In this work, three nanofibrous structures of materials were prepared by electrostatic spinning: pure polyvinylidene fluoride (PVDF), pure polyamide-6 (PA6) and their mixed combination PVDF / PA6. Non-destructive analyzes such as Raman spectroscopy, FTIR, XPS and electron microscopy were used to study the properties of nanofibers. Analyzes confirmed the positive effect of electrostatic spinning of polymers on the support of the formation of highly polar crystalline -phase in PVDF and , -phase in PA6. The structure arrangement of the nanofibrous material and their defects were observed by scanning electron microscopy (SEM). Furthermore, the contact angle of the wettability of the liquid on the surface was measured for the materials, and the permittivity was measured to monitor the dielectric properties. The described results make the mixed material PVDF / PA6 very promising for further research in the field of nanogenerators and functional textiles.
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Electrospinning of polyvinylidenfluoride based fibers
Hošek, František ; Šťastný, Přemysl (referee) ; Částková, Klára (advisor)
Electrospinning is one of the rapidly developing methods for obtaining fibers of very small thickness. There is a wide-scale use of nanofibers, and it has a great potential in many fields, such as in medicine, biology, chemistry, electronics, environmental protection, energy-harvesting, and other. Polyvinylidene fluoride (PVDF) appears to be a promising material for fiber production for its excellent mechanical and chemical properties. It is a chemically inert substance, very resistant to thermal stress. The aim of this bachelor thesis is the preparation of PVDF fibers by electrospinning and the study of the influence of three different surfactants on the spinnability of PVDF, on the arrangement and the shape of fibers which are formed during electrospinning. The effect of surfactant concentration (1 wt%; 0.5 wt%; 0.25 wt%) on the spinning process at electrical voltages of 25 kV and 50 kV was studied. The theoretical part describes the properties and the division of polymers and looks at polyvinylidene fluoride (PVDF) as a source material in more detail. Furthermore, the electrospinning method is described, including process conditions and external parameters influencing the process of obtaining fibers. The experimental part describes the preparation of samples by electrospinning and their characterization. Fiber thickness, its appearance, arrangement, and the occurrence of defects when using individual surfactants were evaluated. It was found that the used ionic surfactants affect the thickness of the fibers and their morphology. Homogeneous fibers with a predominant arrangement in one direction, without defects, were obtained.
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Heating Module for the Electrospinning Electrode
Lukesle, Václav ; Musil, Vladislav (referee) ; Pokorný,, Marek (advisor)
The thesis deals with the principal heating design of the electrospinning electrode. These electrodes are fed with high voltage (tens of kV), which is an essential part of the device for the nanofibres production. This thesis presents the research of possible solutions of the heating and also it analyzes some principles of the nanofibre production. Furthermore, the work presents electrical schematics and PCB of the heating module. The aim of this work is to propose such a solution of heating that makes spinning from melt realizable in the device for 4SPIN ® nanofibres production.
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Nanofibrous Separators for Lithium-Ion Batteries
Pléha, David ; Míka, Martin (referee) ; Janderka,, Pavel (referee) ; Novák, Vítězslav (advisor)
Nanofibrous separators use in lithium-ion batteries brings many advantages. In contrast to contemporary used commercial separators, nanofibrous ones exhibit higher temperature resistance,ionic conductivity and higher electrolyte uptake. Better ionic conductivity is ensured by porous structure and large specific surface. Fibers creates channels for the ionic species motion. Amorphous texture of nanofibers allows quick lithium ionic species motion within the polymeric matrix of separator. Furthermore, these separators exhibit higher volume of uptaken electrolyte. Further advantage of electrospinned nanofibrous separators are both high porosity and chemical stability.
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Electrical characterization of flexible nanofiber piezoelectric materials
Pokorná, Romana ; Holcman, Vladimír (referee) ; Tofel, Pavel (advisor)
This bacherol thesis is focused on piezoelectric nanofibrous materials. The first part describes the formation, use and possible aplications of nanofibers. It further analyze the principle of piezoelectric effect. It is a conversion of mechanical energy into electric energy and conversely. The second part is focused on design of experimental workplace for measurement of functional material properties. The last section of the thesis is dedicated to the electrical characterization of PVDF nanofibers and to the measurement of the piezoelectric charge constant.
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Electrospinning of bioglass and glass-ceramic fibers
Kozáková, Zdenka ; Šťastná, Eva (referee) ; Částková, Klára (advisor)
Bachelor thesis is focused on the preparation of fibers based on bioglass and glass ceramics. The theoretical part of the work summarizes the division and description of biomaterials and their use in biomedical applications. The main part of the work deals with the preparation of bioglass with a focus on the preparation by electrospinning. Experimental part is focused on the preparation of fibers based on bioglass by electrospinning. Different types of bioglass precursors were studied and their spinnability, morphology and bioactivity of the prepared fibers were assessed. The fibers were analyzed by scanning electron microscopy and interactions in simulated body fluid. Fibers prepared from bioglass 45S5 and polyvinylalcohol precursor were evaluated as promising for biomedical applications.
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Studies towards the Preparation of Organic-Inorganic Hybrid Silica Fibers via Electrospinning
Koukolová, Anna ; Dzik, Petr (referee) ; Hüsing, Nicola (advisor)
Polyorganosilany spadají do skupiny hybridních materiálů třídy II, které nabízejí nové možnosti materiálových funkcí a jejich vlastností. Ačkoliv byly v této kategorii již některé materiály zkoumány a stejně tak i jejich aplikace, nebyly doposud vlákna na základě polyorganosilanu v mikro a nano rozměru popsány což bylo motivací pro tuto práci. Předkládaná diplomová práce se zabývá podrobným zkoumáním poly(vinylmethyldimethoxysilanu) jako možného prekurzoru pro elektrostatické zvlákňování. Za účelem přípravy polymeru na bázi vinylmethylsilanu byla provedena radikálová polymerace a podmínky reakce byly modifikovány se záměrem změny molekulové hmotnosti získaného polymeru. Stupeň polymerace byl upravován na základě změny koncentrace iniciátoru a byl stanovován dynamickým rozptylem světla v roztoku polymeru a spektroskopickou metodou nukleární magnetické rezonance. Elektrostatické zvlákňování je velkou měrou spojeno s vlastnostmi roztoku a důraz byl proto kladen právě na zjištění těchto vlastností. Na základě experimentů bylo zjištěno, že syntetizovaný polymer je na přípravu vláken vhodný. Nicméně byly získány i fragmenty vláken a to s využitím polymeru v roztoku methanolu. Předpokladem zvlákňování je dostatek propojení mezi polymerními řetězci. Tento přístup byl studován se zapojením sol-gel postupu a bylo zjištěno, že fáze sol-gel procesu je velmi významná s ohledem na tvorbu vláken. Dalším využitým postupem pro získání vláken bylo začlenění dalšího polymeru do směsi jako nosiče a tímto postupem byla získána vlákna s různým průměrem.
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