This thesis is aimed at preparation of thin plasma-polymerized films deposited on glass fibers by Plasma-Enhanced Chemical Vapor Deposition (PE CVD) from a mixture of tetravinylsilane (TVS) and oxygen gas. Plasma-polymerized films which were deposited on silicon wafers were used to characterize chemical properties and optimization of deposition process with respect to reproducibility.

Plasma polymer films of tetravinylsilane and mixture of tetravinylsilane and oxygen gas were deposited on silicon wafers. Oxygen gas was mixed in tetravinylsilane to improve the compatibility of thin films on glass substrates. Mass spectroscopy was employed during the cleaning of the deposition chamber to check residual gases and process gases, during plasma deposition to monitor neutral plasma species and to follow plasma stability.

Presented master’s thesis is focused on the study of the elementary inactivation processes acting during sterilization of procaryotic systems in dielectric barrier discharge (DBD). Sterilization is an important biomedical and food-industry application and plasma sterilization is one of the methods, which are suitable for sterilization of heat and chemical sensitive materials. Biologically contaminated samples were treated in dielectric barrier discharge operated at atmospheric pressure. The discharge was generated in argon and in nitrogen. The plasma power density was 2725,93 mW cm–3 in argon and 2325,93 mW cm–3 in nitrogen. Gram positive bacteria Bacillus subtilis and gram negative bacteria Escherichia coli were used as a bioindicator. Bacteria were spread onto the surface of Whatman No.1 filtration paper. The influence of UV radiation, reactive species, heat and plasma discharge where the synergistic function of all of the agents was studied. Effects of UV radiation and temperature were studied separately. In order to separate the effect of UV radiation generated by DBD the quartz glass transmitting UV radiation was employed. During the plasma exposition selected samples were covered with the quartz window while other samples were directly exposed to the plasma. Covered samples were exposed to UV radiation and temperature (which cannot be eliminated), samples without quartz window were directly plasma exposed (treated). Results show that for covered samples the lower inactivation was reached than by the samples directly exposed to plasma. When studying the effect of temperature, the temperature between the DBD electrodes was measured by means of a thermocouple. Afterwards the samples were placed in an oven and exposed to the same temperature as was measured between the electrodes. By comparing the results of heat treated samples and plasma treated samples it can be assumed that the influence of the temperature during the sterilization process in DBD is very low. The discharge parameters were studied by means of the Optical Emission Spectroscopy. Plasma treated samples were assessed employing Scanning Electron Microscopy (SEM). Damage of Bacillus subtilis cell wall due to the effect of plasma was observed while no effect of plasma on the structure of filtration paper was detected.

High performance polymer composites are materials with emphasis on specific chemical and mechanical properties due to their broad scope of applications. The main advantages are high strenght and toughness in comparison with their low weight and density. An increased adhesion at composite interfaces is important to ensure excellent composite properties. Bundles of glass fibers were coated by plasma-polymerised interlayers of tetravinylsilane (pp-TVS) of different thicknesses and at different effective powers. The prepared interlayers of pp-TVS were analyzed to evaluate chemical composition (RBS, FTIR, XPS) and mechanical properties (NI-AFM). Microindentation test and fiber-bundle pull-out test were used to determine the interfacial shear strenght.

The overall goal of the presented dissertation thesis was to study the sterilization efficiency of dielectric barrier discharge operated at atmospheric pressure. The fungi Aspergillus niger, gram-positive bacteria Bacillus subtilis and in some experiments also gram-negative bacteria Escherichia coli were used as a bio-indicator enabling to evaluate the effect of plasma assisted microbial inactivation. The samples of microorganism were placed on paper Whatman 1 or PET foil and exposed to plasma. The plasma was generated in argon, nitrogen, synthetic dry/humid air with frequency up to 10 kHz and plasma power density in the range of 1,2-2,9 W/cm3 (according to the process gas). The influence of process gas, plasma power density, plasma exposition time, type of microorganism and material of the substrate on the sterilization effect of dielectric barrier discharge was evaluated. Furthermore the contribution of each single mechanism (UV radiation, temperature and reactive species) to the sterilization effect of plasma and influence of gas humidity was evaluated. The DBD was analysed by means of optical emission spectroscopy, thermocouple was used to measure temperature during a sterilization process. In order to verify the mechanical damage of the microbial cell or the substrates during the plasma process the samples were studied by scanning electron microscopy. Generally, on the basis of experimental results, at increasing treatment times, the remaining number of spores (CFU) decreased. Similarly at increasing the plasma power input, the sterilization rate increased. When sterilising the spores of A. niger in plasma using different process gasses, the efficiency of plasma sterilization decreased as follows: argon, humid synthetic air, nitrogen and dry synthetic air. The results observed in argon plasma using different microorganism demonstrated that the sensitivity of vegetative cells resp. spores to DBD decreased as follows: A. niger spores, B. subtilis vegetative cells, E. coli vegetative cells and B. subtilis spores. Simultaneously results observed for sterilization of spores and vegetative cells of B. subtilis and A. niger demonstrated that the spores are generally more resistant to plasma than are the corresponding vegetative cells. Combining the results of contribution of each single mechanism, optical emission spectroscopy and inactivation characteristic it was found out that the reactive species significantly contribute to the plasma sterilization in all process gasses. Furthermore the inactivation process can be partly assisted by UV radiation and also the temperature can contribute in limited extent to inactivation process in some gasses. The contribution of UV radiation to the plasma sterilization decreased as follows: nitrogen, argon, dry syntetic air and humid syntetic air. Moreover it was found out that the contribution of each single mechanism can be species dependent, this is due to the different response of microorganism to the unfavorable external conditions. SEM analysis of the substrates prooved the etching actions of the plasma generated in all process gasses on the surface of the PET foil. The several minute plasma exposition of the PET foil resulted in the occurence of the „hole corrosion“ on the PET surface. Contrary to these there were no visible changes observed in the paper structure.

Smooth fluorocarbon plasma polymer films have been for a long time considered for fabrication of hydrophobic and slippery coatings. Interest in fluorocarbon materials was also supported by their excellent self-lubricant, dielectric properties and chemical inertness. This thesis is focused on development of new methods for fabrication of fluorocarbon plasma polymes, which could combine the chemical composition and the physical structure necessary for reaching superhydrophobic character of coatings. Poly(tetrafluoroethylene) was the subject material. RF magnetron sputtering using gas aggregation cluster source was the method adapted to fabricate fluorocarbon nanostructured films with chemical composition close to conventional bulk PTFE, but with high degree of cross- linking and branched structure. A model of growth of such plasma polymer nanostructures was discussed.

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...

The main subject of this diploma thesis is the study of the effect of humidity on the total sterilization effect of the dielectric barrier discharge. Sterilization is a process which can eliminate all forms of life. The plasma sterilization is one of the methods that are suitable for sterilization of temperature and chemical sensitive materials. This sterilization method was proved to be effective on the wide spectrum of procaryotic and eucaryotic microorganisms. Basically, the main inactivation factors for cells exposed to plasma are heat, UV radiation and various reactive species. Dielectric barrier discharge (DBD) operating at atmospheric pressure was used for the sterilization of the samples. The discharge was generated in dry air and in humid air. The plasma power densities were 2 160 mW.cm-3, 2 279 mW.cm-3 and 2 760 mW.cm-3 (dry air) or 2 326 mW.cm-3 and 2 850 mW.cm-3 (humid air). Humidity of air was achieved using a wash bottle filled with water through which air flowed into the DBD reactor. Fungi spores of Aspergillus niger were used as model microorganisms. Whatman paper No. 1 was used as the carrying medium. When comparing sterilization efficiency of humid and dry air operating at the same conditions, the higher sterilization effect was observed in humid air. The sterilization effect of the DBD generated in air was compared with results obtained during plasma generation in argon and nitrogen. At the same conditions, the highest sterilization effect was observed in argon, followed by humid air, nitrogen and dry air. It was found out that in our experimental setup the active species are probably the main inactivation mechanism. The influence of temperature on the inactivation of microorganisms was completely negligible. The discharge parameters were studied by means of the optical emission spectroscopy (OES). Plasma treated samples were analyzed employing scanning electron microscopy (SEM). Damage of the microorganisms due to the effect of plasma as well as plasma effect on the structure of the carrying medium was evaluated.

This diploma thesis was focused on the possibility of using a plasma nozzle to accelerate the wound healing process. The benefits of using low-temperature plasma in medicine or biomedical applications are known from many studies, and low-temperature plasma is already used to sterilize medical devices, materials or surgical instruments. Some studies also report a high potential of usinh plasma nozzle in the treatment of skin wounds. In the experimental part of this work, an in vitro wound healing test was performed using two different low-temperature plasma sources. Source No. 1 was a surface wave microwave discharge and source No. 2 was a torch microwave discharge. An in vitro scratch healing test was performed on a monolayer of HaCaT keratinocytes and testing was performed using various parameters. The influence of the plasma treatment time was monitored, as well as the influence of the plasma discharge power and also the influence of the argon working gas flow. Especially when using a torch microwave discharge, faster wound healing was recorded at most of the parameters used compared to the control. Thus, it can be said that this source appears to be potentially suitable for faster wound healing. Furthermore, in the work using the MTT cytotoxicity test, the viability of skin cells after their plasmination was also monitored using the same conditions as in the in vitro wound healing test. When performed in the standard MTT assay, none of the settings or sources used showed any cytotoxic effects on keratinocytes. LDH cytotoxicity tests were also performed concurrently to verify the accuracy of the MTT assays. The results of both tests agreed and the use of low-temperature plasma in skin treatment can be considered as safe. Overall, the results show that the plasma nozzle can find use in medicine in the healing of skin wounds and chronic defects as a potentially fast, inexpensive and effective method.

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).