|
|
Kinetic study of excited state proton transfer in polymer-surfactant system
Bačová, Jana ; Vala, Martin (referee) ; Mravec, Filip (advisor)
In this bachelor thesis were studied interactions between hyaluronic acid and cationic septonex by steady-state and time-resolved fluorescence with fluorescence probes pyrene and 1-naphthol. At first was determined critical micelle concentration of septonex. In the case of both fluorescence probes was studied area below and above critical micelle concentration. It was found, that 1-naphthol undergo very fast deprotonation in aqueous solution, while in the present of micelles the rate of deprotonation is c significantly retarded. In the system of hyaluronic acid – septonex it was observed, that formation of aggregates occurs at lower concentrations than in the system without hyaluronic acid. Molecules of probe are probably distributed between hyaluronic acid – septonex aggregates and free micelles above critical micelle concentration.
|
|
|
Heat insulating moulded refractory materials
Novotný, Radoslav ; Lang, Karel (referee) ; Raschman,, Pavel (referee) ; Havlica, Jaromír (advisor)
Doctoral thesis is focused on the study, research and development of heat insulating moulded refractory materials. The replacement of shaped instead of unshaped refractories is recently and strongly industrially demanded and belongs to ongoing research topics. With the increasing demand of energy savings, the excellent insulation properties are essential. The insulating properties of castables are the result of targeted porosity formation. The porosity is coming from the controlled air intrusion into material resulted to foamed structure. The foaming process was achieved by mixing of separately prepared aqueous foam into raw castable slurry or by in situ foaming of intensively mixed castable slurry with the surfactant additive. Nevertheless, the study of foam behaviour and the influence of additives on binder hydration and setting processes (i.e. calciumaluminate cement) was substantial for successful preparation of the experimental samples. The two types of the experimental samples were prepared. The first one was based on mixing of kaolin slurry with pre-prepared aqueous foam, whereas the de-aglomeration ability of kaolin specie was utilized to water-particle film formation. In situ foaming of multicomponent system is the second one. The both processes brought some negative attributes, so the optimal properties of prepared castables were achieved by their combination.
|
|
|
Fluorescence correlation spectroscopy in colloid systems
Janíček, Tomáš ; Smilek, Jiří (referee) ; Mravec, Filip (advisor)
This work is focused on studying of stability and interaction in colloidal systems created by micelles of surfactant CTAB in solution of hyaluronic acid and water. As method chose for this work was selected fluorescence correlation spectroscopy. As dye was used Nile red. Measurements were divided firstly by size of polymeric chain and secondly by concentration of hyaluronic acid. Purpose of this work was to find out how will CTAB particles react with different sizes and concentration of hyaluronic acid. For comparison to hyaluronic acid was used Poly(sodium-4-styrenesulfonate).
|
|
|
Preparation and characterization of magnetic nanoparticles modified by surfactants
Solnička, Ondřej ; Másilko, Jiří (referee) ; Enev, Vojtěch (advisor)
Theme of this bachelors thesis was preparation and characterization of iron(II, III) oxide nanoparticles. Those nanoparticles were modified by surfactants. The surfactants which were used for modifiation were CTAB, TTAB and Septonex. Prepared and modified nanoparticles were taken for characterization by using methods of elemental analysis, thermogravimetry, dynamic light scattering and transmission electron microscopy (TEM). Results from each measurement shows that nanoparticles modified by CTAB had on average 85.9 nm in diameter, TTAB size was on average 108.3 nm and the last nanoparticles with Septonex had 246.6 nm in diameter on average. Prepared modified nanoparticles except the Septonex ones were stable enough to not aggregate. Septonex modified nanoparticles had greater tendenty to aggregate.
|
|
|
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.
|
|
|
Surfactant organogels as delivery systems for medical and cosmetic oils
Koláčková, Petra ; Mravec, Filip (referee) ; Pekař, Miloslav (advisor)
The aim of this thesis was to investigate the possible using of surfactant organogels in the cosmetic industry. Mainly, we focused on the ability of sugar surfactants to bind with medical (cosmetic) oil. With further heating, we observed transformation to the organogels. During the preparation of sugar surfactants, we decided to use the transesterification method. Another target was to verify functionality of this method and then proposed modifications to this process. Using Nuclear Magnetic Resonance, we checked the chemical structure of our sugar-based surfactants.
|
|
|
Interactions between Hyaluronan and Surface Active Substances
Krouská, Jitka ; Burgert,, Ladislav (referee) ; Lehocký,, Marián (referee) ; Vikegard,, Peter (referee) ; Pekař, Miloslav (advisor)
Vliv hyaluronanu na micelizaci tenzidů byl studován různými fyzikálně-chemickými metodami. Byly zvoleny dva kationaktivní tenzidy, a to tetradecyltrimethylammonium bromid (TTAB) a cetyltrimethylammonium bromid (CTAB). Metoda izotermické titrační kalorimetrie byla využita pro stanovení entalpie micelizace, tenziometrie popisuje povrchové vlastnosti daných vzorků. Byl sledován také vliv různé molekulové hmotnosti použitého hyaluronanu a délka alkylového řetězce tenzidu na agregační chování daného systému. Výsledkem jsou hodnoty kritické micelární nebo agregační koncentrace tenzidu. V neposlední řadě se diskutuje využití agregátů hyaluronan-tenzid jako možné nosiče pro cílenou distribuci léčiv.
|
|
|
Diffusion of dyes in biopolymeric hydrogels
Vyroubal, David ; Mravec, Filip (referee) ; Klučáková, Martina (advisor)
This thesis is focused on diffusion of dyes in biopolymer-based hydrogels. These hydrogels are based on interaction between biopolymer-like electrolytes with oppositely charged surfactants. When polyelectrolytes interact with oppositely charged surfactants, micelle-like nano-containers can be formed. These nano-containers are able of binding hydrophobic compounds. In this study, combination of modified dextran (diethylaminoethyl dextran) with positive charge and oppositely charged sodium dodecylsulphate as surfactant was used for preparation of hydrogels. Next type of hydrogel was based on hyaluronan and positive charged surfactant Septonex (carbethoxypendecinium bromide). As a diffusion probes in hydrogels dyes Nile red and ATTO 488 were used. The diffusion of these dyes from aqeous solutions of NaCl or surfactants into hydrogels was monitored in time. Transport of dyes into structure of hydrogels was characterized by diffusion coefficients and structural parameters of hydrogels.
|
|
|
Microcalorimetric study of interactions between hyaluronan and catanionic vesicular systems
Mach, Jakub ; Pekař, Miloslav (referee) ; Krouská, Jitka (advisor)
Properties of surfactants in water, interactions between oppositely charged surfactants and interactions in system containing didecyldimethylammonium chloride (DDAC), hyaluronan and ion pair amphiphile (IPA) have been studied using isothermal titration calorimetry. For the study of properties of surfactants in water and their mutual interactions, two cationic surfactants have been chosen, namely cetyl trimethylammonium bromide (CTAB) and carbethopendecinium bromide (Septonex), and an anionic surfactant sodium dodecyl sulfate (SDS). For hyaluronan, a molecular weight of 250 450 has been chosen. Critical micelle concentration of the chosen surfactants and enthalpy of the investigated interactions have been determined using the TAM III calorimeter. To prove the interactions in system containing hyaluronan, DDAC and IPA and to determine enthalpy the Microcal PEAQ-ITC calorimeter has been used.
|
|
|
Influence of the preparing of a biopolymer-surfactant complex on its stability and solubilization properties.
Pilgrová, Tereza ; Burgert,, Ladislav (referee) ; Mravec, Filip (advisor)
Influence of the preparing of a biopolymer-surfactant system on its solubilization properties and stability was investigated by using fluorescence spectroscopy and dynamic light scattering methods. Investigation was made on complex of native hyaluronan with cationic surfactant cetyltrimethylammonium bromide (CTAB). System has been studied in aqueous and in saline solutions. The effect of temperature of stock solutions and freezing effect on subsequent properties were investigated. Further was examinated, what effect has a way of introducing fluorescent probe into the system on subsequent solubilization properties. It was found that the conditions of preparing of biopolymer-surfactant system have a significant effect on the solubilization properies and stability of complex.
|
guest ::
