|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Utilization of polynailine in separation methods
Riečan, Martin ; Sobotníková, Jana (advisor) ; Křížek, Tomáš (referee)
Submitted master thesis is by its character focused on development of polyaniline which would possess attributes typical for monolithic stationary phase. Developed polyaniline aims to be used in capillary liquid chromatography. Accompanying target of submitted master thesis is to provide solutions for variety of complications which follow the preparation of polyaniline in its desired form such as consistency in a form of solutions, gels and pastes, extremely fast polymerization reaction, limited solubility of cross-linking agents, solubility of monolithic polyaniline in polar mobile phases and insufficient bond of polyaniline to the inner wall of fused silica capillary tubing. Solutions for this complications are selection of ideal oxidation agent (ammonium persulfate), cross-linking agent (tris(4-aminophenyl)amine) and porogenic agent (methanol). Also, setting ideal ratio between oxidation agent, cross-linking agent and porogenic agent, heat treatment, choice of suitable mobile phase (tetrahydrofuran), adjustment of capillary wall using silanization agent (3-[3-(trimethoxysilyl)propyl]-aniline) and construction of equipment needed for quick filling of capillaries. Described development concluded in the preparation of solid polyaniline monolith which had a steady bond to the inner wall of fused...
|
|
|
Design, fabrication and testing of graphene biosensors
Tripský, Andrej ; Gablech, Imrich (referee) ; Bartošík, Miroslav (advisor)
Pokrok ve vývoji nanotechnologií nám poskytuje dobrou příležitost k vývoji nových špičkových zařízení. Tato práce si klade za cíl vyrobit, popsat a změřit grafenové pH senzory na dvou různých substrátech - polymeru parylenu C a SiO2. Tento pH senzor je prvním krokem ve vývoji nositelné náplasti monitorující stav kůže a možné infekce. Grafen je 2D materiál na bázi uhlíku se zajímavými vlastnosti a nadějnými aplikacemi. Úspěšně jsme provedli dva různé experimenty sloužící k charakterizaci grafenových senzorů a jejich odezvu na různé hodnoty pH. V prvním experimentu jsme použili horní elektrolytické hradlo k určení bodu neutrality (Diracův bod). Druhý experiment popsal změnu rezistence grafenu jako funkce pH. Dále jsme také funkcionalizovali grafen polyanilinem, abychom zlepšili jeho vlastnosti. Prokázali jsme citlivost grafenových senzorů na pH pro oba substráty a objevili jsme několik výzev jako potřebu kontroly iontové síly, experimentů samotných a destrukce grafenu.
|
|
|
Novel materials for membrane gas separation
Giel, Verena ; Pientka, Zbyněk (advisor) ; Izák, Pavel (referee) ; Vopička, Ondřej (referee)
The implementation of polymer membranes in gas separation applications has been investigated to a great extent. Nevertheless, only a few types of polymers are used in commercial applications, disclosing the need for new materials with superior membrane performance to make membrane processes a more competitive technology over the conventional ones. Based on this context, this work focuses on the development of new polymeric membranes. Polyaniline (PANI), a multifaceted polymer that can change its structural properties upon various modification procedures, was chosen as membrane material. PANI membranes possess attractive O2/N2 selectivities, wherefore it is an interesting candidate for the use in gas separation applications, such as generation of oxygen-enriched air or inert gas generation. However, membranes made from neat PANI are suffering from brittleness and thus create leak paths through the membrane. Therefore PANI was blended with polybenzimidazole (PBI), a temperature stable polymer with good film-forming properties facilitating the preparation of thin, stable polymer films. Furthermore, several techniques were investigated including acid-doping, thermal treatment, and addition of titanate nanotubes (TiNTs) to enhance the separation properties. The materials that have been prepared are: 1)...
|
|
|
Chromatographic characterization of polyaniline-coated stationary phases
Taraba, Lukáš ; Křížek, Tomáš (advisor) ; Pacáková, Věra (referee) ; Srbek, Jan (referee)
(EN) This dissertation thesis is focused on physicochemical and chromatographic characterization of polyaniline-coated stationary phases. In the first part, surfaces of bare silica and octadecyl silica sorbents were modified by in-situ chemical polymerization of aniline hydrochloride and their subsequent systematic characterization was performed by using the linear solvation energy relationship approach in the HILIC mode of capillary LC. In addition, several common physicochemical techniques were used to characterize properties of these altered materials. The modified sorbents were then packed into capillary columns. The retention interactions taking place between solute and the separation system were evaluated on the basis of retention data of a number of various solutes. The results showed that polyaniline coating had a significant effect on the retention promoting interactions of both polyaniline-coated stationary phases. The assumed mixed-mode retention mechanism was proven for both the stationary phases. The second part dealt with investigation of the separation potential of polyaniline- coated silica stationary phase in different chromatographic modes. The retention factor curves of structurally similar solutes were constructed as a function of organic modifier portion in the mobile phase....
|
|
|
Preparation and characterization of polyaniline-coated stationary phases doped with silver
Pátereková, Viktória ; Křížek, Tomáš (advisor) ; Sobotníková, Jana (referee)
The aim of this study is a preparation of polyaniline stationary phases doped with silver for application in HPLC. Various polyaniline coated stationary phases differing in the addition of AgNO3 were polymerized. Some of them were subjected to Ag sedimentation, in others AgNO3 was added after polymerization. Stationary phases were investigated by scanning electron microscopy, atomic absorption spectroscopy, Raman spectroscopy, and Fourier transformation infrared spectroscopy. Columns filled with prepared stationary phases were compared with silver-free polyaniline column by separating a mixture consisting of caffeine, theobromine and theophylline in three chromatographic modes (NP-pure ACN, HILIC-98/2 (v/v) ACN/water and RP-20/80 (v/v) ACN/water) at a flow rate of 5 µL/min with UV detection at 265 nm and also by separating a mixture of 2'-aminoacetophenone, 3'-aminoacetophenone and 4'-aminoacetophenone in the same chromatographic modes, at a flow rate of 5 µL/min except from RP mode where a flow rate of 10 µL/min was used to accelerate separation. Polyaniline-coated columns doped with silver showed different selectivity in the RP mode of the mixture of caffeine, theobromine and theophylline when compared to polyaniline-coated columns without the addition of silver. Further, the columns were tested for...
|
|
|
Organic-inorganic polymers - synthesis and characterization of hybrid polymers and nanocomposites
Depa, Katarzyna ; Strachota, Adam (advisor) ; Matějka, Libor (referee) ; Sedláček, Jan (referee)
In the first part of this work, silica nanoparticles and alternative or additional filler phases were incorporated into hydrogels based on the temperature-sensitive poly(N- isopropylacrylamide) (PNIPAm). Nano-SiO2-filled porous PNIPAm hydrogels with an enhanced force response (up to 100 g) to temperature stimuli were obtained by increasing several times the pore wall thickness, which was achieved via reducing the solvent (porogen) content during the gels' cryo-synthesis. A similar optimization of the force response was also carried out for analogous gels reinforced by nano-TiO2, in which the reinforcing effect of the filler is weaker. Partial intercalation of amylopectin starch into divinyl-crosslinked bulk as well as porous PNIPAm gels several times improved their extensibility. In case of starch-rich bulk gels, a very fast and extensive one-way deswelling in response to increased temperature was achieved (re-swelling upon cooling is much slower), which is attributed to specific properties of the starch-PNIPAm interface. In doubly-filled bulk PNIPAm/nano-SiO2/starch gels, a very strong synergic reinforcing effect of both fillers is observed, due to specific hydrogen bridging between the three phases. Highly porous cryogels based on PNIPAm/nano- SiO2/starch displayed a highly improved extensibility...
|
|
|
The Study of the Molecular Structure of Various Forms of Conducting Polymers using FTIR and Raman Spectroscopies
Morávková, Zuzana ; Trchová, Miroslava (advisor) ; Baumruk, Vladimír (referee) ; Matějka, Pavel (referee)
In this Thesis, the structure of thin films formed by a conducting polymer, polyaniline, was studied using mainly infrared and Raman spectroscopies. That led to the study of aniline oligomers. The oligomers play a key role in the formation of thin films and nanostructures of polyaniline. Furthermore, the Thesis deals with the carbonization of various forms of polyaniline (granular polyaniline base, thin films of polyaniline salt, multi-wall carbon nanotubes coated with polyaniline salt or base, polyaniline nanotubes/nanorods prepared in the presence of ethanol). The two topics, aniline oligomers and carbonization of polyaniline, are connected by a paper concerning the carbonization of microspheres formed during oxidation of aniline in alkaline medium. Optical microscopy, transmission and scanning electron microscopy, UV-Vis spectroscopy, spectroscopic ellipsometry, wide angle X-ray scattering and thermogravimetric analysis were used.
|
|
|
The Study of the Molecular Structure of Various Forms of Conducting Polymers using FTIR and Raman Spectroscopies
Morávková, Zuzana
In this Thesis, the structure of thin films formed by a conducting polymer, polyaniline, was studied using mainly infrared and Raman spectroscopies. That led to the study of aniline oligomers. The oligomers play a key role in the formation of thin films and nanostructures of polyaniline. Furthermore, the Thesis deals with the carbonization of various forms of polyaniline (granular polyaniline base, thin films of polyaniline salt, multi-wall carbon nanotubes coated with polyaniline salt or base, polyaniline nanotubes/nanorods prepared in the presence of ethanol). The two topics, aniline oligomers and carbonization of polyaniline, are connected by a paper concerning the carbonization of microspheres formed during oxidation of aniline in alkaline medium. Optical microscopy, transmission and scanning electron microscopy, UV-Vis spectroscopy, spectroscopic ellipsometry, wide angle X-ray scattering and thermogravimetric analysis were used.
|
guest ::
