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Synthesis of nanoparticles using gas aggregation sources
Hanková, Adéla ; Kylián, Ondřej (advisor) ; Shukurov, Andrey (referee)
This work focuses on the synthesis of thin films and nanoparticles of vanadium and its oxides. Thin films are fabricated by means of magnetron sputtering, while for the prepara- tion of nanoparticles a gas aggregation source is used. Produced thin films and nanopar- ticles are investigated and compared in terms of their morphology, optical properties and chemical structure. We also study the heating of both types of samples. All em- ployed diagnostics methods prove that oxidation of films and nanoparticles at 550 řC changes the samples to crystalline V2O5. Another investigated method of vanadium oxide nanoparticles preparation is based on the addition of oxygen into the deposition chamber. Changes in shape, size, bulk composition and thickness of the deposited layer of nanoparticles are demonstrated in comparison with nanoparticles fabricated in a pure argon atmosphere. On the other hand, the surface composition is similar for both meth- ods of preparation indicating spontaneous oxidation of the surface layer of both materials on ambient air. 1
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Deposition of Nanocomposite Thin Films
Kratochvíl, Jiří ; Kylián, Ondřej (advisor)
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...
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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...
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Nanostructured surfaces for biomedical applications
Kratochvíl, Jiří ; Kylián, Ondřej (advisor) ; Baroch, Pavel (referee) ; Čech, Vladimír (referee)
Nanostructured thin films deposited by magnetron sputtering and gas aggregation sources of nanoparticles are studied especially with regards to their use in biomedical applications. The possibility of using plasma polymers for the preparation of antibacterial coatings is tested first. It is presented that sputtered nylon 6,6 films may be impregnated by antibiotics. The subsequent release of antibiotics from such prepared reservoirs may be tuned by their thickness, chemical composition, or by an additional barrier layer. The second studied type of antibacterial coatings is based on metallic nanoparticles overcoated with sputtered PTFE. It is shown that by a proper choice of the number of nanoparticles and thickness of fluorocarbon overlayer, a significant antibacterial effect can be achieved while maintaining the biocompatibility of produced nanocomposite coatings. The possibility to enhance the antibacterial effect by impregnation of plasma polymer/nanoparticle nanocomposites by antibiotics is also verified. Nanoparticle sources are used to study two-component films with 2D gradient character, too. A simple analytical model is developed allowing description and design of such nanomaterials. Its suitability is experimentally verified on 2D gradients combining Ag and Cu nanoparticles. Finally, an original...
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Fractal growth of polyethylene nanoislands on polyethylene oxide thin films
Májek, Juraj ; Ryabov, Artem (advisor) ; Kylián, Ondřej (referee)
Plasma polymer fragments deposited from vapor on non-wetting polymer substrates are seen to aggregate into fractal nanoislands. Dependent on conditions of the experiment, the islands attain diverse shapes ranging from dendritic snowflakes, branching seaweed to twisting snakes. In our work, we identify dominant kinetic processes responsible for this diversity and relate them to physical characteristics of the experiment. We review and implement basic computer models of deposition and ag- gregation of diffusing particles: The Diffusion-Limited Aggregation (DLA), both on a lattice and without a lattice, and the Cluster-Cluster Aggregation (CCA). The off-lattice DLA yields isotropic random fractals. The lattice DLA fractals are influenced by the properties of the lattice itself, which can be chosen to represent the symmetry of the substrate layer on which the islands grow. Fractals generated in the CCA model are more linear. Com- petition between diffusion and deposition rates gives a transition between off-lattice DLA and CCA fractals. Each of these models comprises a mechanism that we conjecture to be dominant during growth of distinct observed polyethylene nanoislands. Thus the multiple observed fractal shapes allow us to draw conclusions on micro- scopic kinetics of the surface diffusion of deposited...
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Deposition of Nanocomposite Thin Films
Kratochvíl, Jiří ; Kylián, Ondřej (advisor)
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...
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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...
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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...
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Dynamics of drying of sessile droplets in dependence on the surface wettability
Štefaníková, Radka ; Kylián, Ondřej (advisor) ; Shukurov, Andrey (referee)
Wettability is one of the key parameters that govern interaction between solid objects and their surrounding environment. In this work wettability of two kinds of materials was investigated - untreated and plasma treated polyether ether ketone and nanostructured C:F thin films deposited either onto a smooth substrate or on substrates seeded with nanoparticles. In the first case the main focus was given to the evaluation of dependence of wettability and water droplet drying dynamics on the plasma treated PEEK on storage time. It was found that plasma treatment induces changes in surface morphology and in chemical composition that in turn results in dramatic increase of surface wettability as well as in alteration in drying dynamics. It was shown that whereas chemical composition and wettability gradually approach properties observed on untreated PEEK, the drying dynamics, namely disappearance of the constant contact angle phase, is temporally stable. In the second case the main emphasis was given to the investigation of the effect of surface nanoroughness and its character on wettability of produced samples. It was found that when the base layer was composed from nanoparticles of the same kind, the surfaces exhibited higher values of water contact angles as compared to C:F films deposited onto smooth...
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Modification of polymeric materials by means of atmospheric plasma for biomedical applications
Kretková, Tereza ; Kylián, Ondřej (advisor) ; Hanuš, Jan (referee)
Polymeric materials are thanks to their advantageous volume properties and due to their relatively low price interesting for various applications. However, the possible use of common polymers is hampered by their low surface energy that leads to poor adhesion of subsequent coatings and limited ability to bind biomolecules. One of the strategies to increase the surface energy is modification of polymer surface by atmospheric plasma. In this study, we have investigated effect of atmospheric pressure dielectric barrier discharge generated in air on poly(ether-ether-ketone). We estimated plasma composition by optical emission spectroscopy as well as monitored temperature of the polymer during the treatment in order to verify applicability of this plasma source. Subsequently changes in morphology, chemical composition and surface energy of polymeric samples after the plasma treatment were determined. We proved that surface energy increases with increasing surface density of polar functional groups and that plasma causes changes in morphology of the studied polymer surface. We determined the etching rate of poly(ether-ether-ketone) in dependence on the supplied power. Optical properties remained unchanged indicating that also volume properties were not affected by plasma. Finally we tested the binding of...
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