|
|
Preparation of nanoparticles of transition metals and their oxides using gas aggregation sources
Hanková, Adéla ; Kylián, Ondřej (advisor) ; Khalakhan, Ivan (referee)
This work focuses on the synthesis of nanoparticles of vanadium, titanium and their oxides. Magnetron-based gas aggregation source was used for nanoparticle preparation. Metallic nanoparticles of vanadium and titanium deposited on substrate were heated at atmospheric pressure which transformed them into oxides. Metallic and oxide nanopar- ticles are compared in terms of morphology, chemical composition, crystal structure and optical properties. Oxidation of vanadium nanoparticles during short heating times at the temperature of 450 řC is discussed in more detail. It was demonstrated, that ideal heating time for VO2 preparation is 60 s, the most stable vanadium oxide phase - V2O5 - is formed after longer heating. The change of electrical and optical properties with tem- perature (thermochromic behaviour) was monitored for VO2 nanoparticles. The V2O5 and TiO2 nanoparticles were tested for their photocatalytic effect and possible use as substrates for surface-enhanced Raman spectroscopy (SERS). It was shown that TiO2 nanoparticles coated with a thin silver layer can be used as recyclable, enhancing SERS substrates. 1
|
|
|
Modification of polymeric substrates by means of non-equilibrium plasma
Kuzminova, Anna ; Kylián, Ondřej (advisor) ; Čech, Vladimír (referee) ; Novák, Stanislav (referee)
Title: Modification of polymeric substrates by means of non-equilibrium plasma Author: Anna Kuzminova Department: Department of Macromolecular Physics Supervisor of the doctoral thesis: doc. RNDr. Ondřej Kylián, Ph.D. Abstract: Processing of polymeric materials by means of non-equilibrium plasma is a topic that reaches increasing attention, which is due to the wide range of possible applications. As an example can be mentioned processing of polymeric foils used for food packaging, where plasma treatment enables to improve their functional properties (e.g. increase their printability or enhance their barrier properties). In the frame of this PhD. thesis two different strategies suitable for the modification of polymeric materials were followed. The first one was based on treatment of polymers by atmospheric plasma. The main attention was devoted to the investigation of influence of atmospheric pressure plasma on surface properties of 8 commonly used polymers, namely on their chemical composition, morphology and wettability. In addition, it was observed that plasma treatment causes also alteration of their mechanical properties, may lead to their substantial etching and in some cases improves their biocompatibility. The second studied strategy was based on coating of polymers with thin functional...
|
|
|
Diagnostics of plazma in the deposition sources using the Langmuir probes
Šedivý, Petr ; Kousal, Jaroslav (advisor) ; Kylián, Ondřej (referee)
This experimental work is concerned with measurement of elementary characteristics of plasma - potential of plasma, electron temperature and density of particles. As research methods were selected the Langmuir probes - especially the single probe. At the beginning of the thesis there are explained shortly the elementary characteristics of plasma and the procedure of determination particular parameters of the plasma from the volt-ampere characteristics of the probe. The third chapter is focused on description of the experiment, the probe, the apparatus and its control. Plasma measured within this work originated from the new hollow magnetron which will serve as future source of nanoparticles. Results of the work are focused on the description of individual parameters of the plasma in dependence on other variables such as the magnetron power, pressure of gas, spatial dependence or presence of additional auxiliary magnetic field.
|
|
|
Adhesion, growth and differentiation of osteoblasts and mesenchymal stromal cells on biocompatible nanomaterial surfaces
Brož, Antonín ; Hubálek Kalbáčová, Marie (advisor) ; Černý, Jan (referee) ; Kylián, Ondřej (referee)
The thesis is based on articles describing the fundamental research of carbon based nanomaterials for their possible utilization in biomedicine. The aim of this thesis was to describe the way how human osteoblasts (SAOS-2 cell line) and primary human mesenchymal stem cells (hMSC) adhere, grow and behave on surfaces made of several carbon allotropes - nanocrystalline diamond (NCD), single walled carbon nanotubes (SWCNTs) films and graphene. The utilization of carbon as the basic material promised good biocompatibility and possibility of useful surface modifications. The NCD had modified surface nanotopography (nanoroughness and nanostructuring prepared by dry ion etching). All the materials had modified surface atomic termination with oxygen and hydrogen which changes the surface electrical conductivity, surface charge and wettability. It was hypothesized that the surface termination can also influence the cell adhesion and growth. It turned out that all the studied materials were suitable as substrates for cultivation of mentioned cell types. Various nanoroughnesses of NCD surface had different effect on the cell adhesion and cell metabolic activity. Nanostructuring of the NCD influenced the formation of focal adhesions. The surface terminations of NCD and the other studied nanomaterials in...
|
|
|
Deposition of Nanocomposite Thin Films
Kratochvíl, Jiří ; Kylián, Ondřej (advisor) ; Straňák, Vítězslav (referee)
Nanocomposite thin films can find application in photovoltaics, optics, fabrication of sensors, or in biomedicine. This work investigates fabrication and characterization of thin metal-plasma polymer nanocomposite films which have direct application because of their unique optical properties (e.g. SERS - Surface-Enhanced Raman Spectroscopy) or antibacterial effects (biomedicine). We fabricated metal nanoparticles either by magnetron sputtering (island growth) or by means of gas aggregation source of nanoparticles, thereby we got nanoparticles with very different morphologies. We used silver as a material for nanoparticles because of its antibacterial effects. We incorporated these nanoparticles into sputtered Nylon and sputtered PTFE (polytetrafluoroethylene) plasma polymer matrix. These two polymers have very different chemical structure and related different surface energy. First, we compared growth of nanoparticles on substrates of sputtered Nylon and PTFE. Then we compared properties of sandwich nanocomposites polymer-Ag-polymer for both types of nanoparticles and for both matrix materials. We characterized produced thin films especially with respect to their stability in water (antibacterial films), thermal stability (sterilization by heating) and stability on the open air (storage). Finally, the tests...
|
|
| |
|
|
Ultrathin films deposited by means of magnetron sputtering and their characterization
Petr, Martin ; Kylián, Ondřej (advisor) ; Straňák, Vítězslav (referee) ; Tichý, Milan (referee)
Presented work is focused on the deposition and characterization of thin and ultrathin plasma polymer films, then also on the preparation of nanocomposites metal/plasma polymer. The characterization of plasma polymer films was partly done in-situ without exposing the samples to the atmosphere. The thickness of prepared films was measured by spectral ellipsometry, the chemical composition was measured by XPS. The morphology and optical properties of deposited films were measured ex-situ. It is shown that during the initial stages of growth the properties of plasma polymer films depend on their thickness and also on the material of the substrate. Many interesting applications were explored for prepared nanocomposites metal/plasma polymer. They can be used as superhydrophobic coatings, gradient coatings, substrates for Raman spectroscopy or as antibacterial coatings. Moreover, special optical properties of prepared nanocomposites were studied in detail. Presented work has an experimental character.
|
|
|
Heterogeneous metal-plasma polymer nanoparticles prepared by means of gas aggregation sources
Štefaníková, Radka ; Kylián, Ondřej (advisor) ; Kousal, Jaroslav (referee)
The field of nanoparticle preparation is nowadays rapidly evolving. Most of the ap- proaches can be classified as wet chemistry techniques. On the other hand, gas aggrega- tion sources offer an alternative, purely physical approach of how to fabricate nanoparti- cles in a controlled and reproducible manner. Many kinds of nanoparticles were already produced in this way, e.g. metallic, metal oxides or plasma polymer nanoparticles. Moreover, as it was demonstrated in recent studies, even heterogeneous nanoparticles by combining more types of materials may be produced by such sources. Among them, an increasing interest is devoted to the metal/plasma polymer nanoparticles. Concerning the production of metal/plasma polymers nanoparticles, the majority of so far published studies focused on the nanoparticles with metallic cores surrounded by a plasma polymer overcoat. Because of this, we decided to investigate a novel two- step deposition procedure for the production of metal/plasma polymer nanoparticles with inverse structure, i.e. nanoparticles with plasma polymer cores covered by metal. This method is based on the gas aggregation technique for plasma polymer nanoparticle fabrication (C:H:N:O in this study) followed by subsequent in-flight coating by sputtered metal (silver, copper and titanium). The production...
|
|
|
Fabrication of metal nanoclusters and their characterization
Kratochvíl, Jiří ; Kylián, Ondřej (advisor) ; Kousal, Jaroslav (referee)
Copper nanoclusters have potencial for fabrication of nanostructured surfaces, which can be used in electronics, electrotechnics, optics and in biomedical applications. To create such surfaces, it is necessary to create and characterize the nanoclusters deeply first and this is the main topic of this work. First, we found repeatable procedure to create copper nanoclusters by the gas aggregation nanocluster source. We studied homogenity of prepared surfaces by quartz crystal microbalance and optical ellipsometry, we determined conditions for deposition of homogeneous coatings. Next, we studied deposition rate in dependence on the magnetron current, pressure in the aggregation and deposition chambers. Deposition rate linearly increased with current, but in low currents it was nearly zero. Furthermore, we found maximum deposition rate for a given pressure in the aggregation chamber and determined the range of pressure in deposition chamber where it is possible to deposit thin films of copper nanoclusters. This is important for fabrication of nanocomposite surfaces. We studied also the size, shape of nanoclusters and growth of surface by scanning electron microscope. The surfaces were very porous. We measured roughness and optical absorbance where anomalous optical absorption was found. Finally, we found that...
|
|
|
Influence of non-equilibrium plasma on seeds
Červenková, Veronika ; Kylián, Ondřej (advisor) ; Solař, Pavel (referee)
Agriculture was, is and will always be one of the most important economic sectors owing to its primary purpose: the global food security. Forming the base pillar of the so- ciety's system, it is the privilege of nations to make their products accessible to everyone, regardless of the environmental or economical conditions. The employment of the newest technologies in order to secure its regulation gave rise to a brand new field of science - plasma agriculture. Plasma agriculture examines the use of non-thermal plasma on natural sources with diverse objectives. Soil rehabilitation, microbial food decontamination or insecticide acti- vities are not the only examples. In this thesis we shall devote to the DBD air plasma application on the Pumpkin seeds (sort Small Sugar) in order to improve its germination. After verifying the selected plasma source impact on eight polymer foils the main focus was given to the seeds. It was found that the plasma treatment induces changes in the chemical composition and water droplet drying dynamics that in turn result in dramatic increase of surface wettability. These changes must not have been accompanied by the burning; otherwise the treatment led to a radical disruption of seeds' morphology and to failure of the essential - enhancement of the germination rate. 1
|
guest ::
