Das Ziel dieser Arbeit ist neben der Synthese von Sol-Gel-Funktionsschichten auf der Basis von transparent leitfähigen Oxiden (transparent conducting oxides, TCOs) die umfassende infrarotoptische und elektrische Charakterisierung sowie Modellierung dieser Schichten. Es wurden sowohl über klassische Sol-Gel-Prozesse als auch über redispergierte Nanopartikel-Sole spektralselektive Funktionsschichten auf Glas- und Polycarbonat-Substraten appliziert, die einen möglichst hohen Reflexionsgrad im infraroten Spektralbereich und damit einhergehend einen möglichst geringen Gesamtemissionsgrad sowie einen niedrigen elektrischen Flächenwiderstand aufweisen. Zu diesem Zweck wurden dotierte Metalloxide, nämlich einerseits Zinn-dotiertes Indiumoxid (tin doped indium oxide, ITO) und andererseits Aluminium-dotiertes Zinkoxid (aluminum doped zinc oxide, AZO)verwendet. Im Rahmen dieser Arbeit wurden vertieft verschiedene Parameter untersucht, die bei der Präparation von niedrigemittierenden ITO- und AZO-Funktionsschichten im Hinblick auf die Optimierung ihrer infrarot-optischen und elektrischen Eigenschaften sowie ihrer Transmission im sichtbaren Spektralbereich von Bedeutung sind. Neben der Sol-Zusammensetzung von klassischen Sol-Gel-ITO-Beschichtungslösungen wurden auch die Beschichtungs- und Ausheizparameter bei der Herstellung von klassischen Sol-Gel-ITO- sowie -AZO-Funktionsschichten charakterisiert und optimiert. Bei den klassischen Sol-Gel- ITO-Funktionsschichten konnte als ein wesentliches Ergebnis der Arbeit der Gesamtemissionsgrad um 0.18 auf 0.17, bei in etwa gleichbleibenden visuellen Transmissionsgraden und elektrischen Flächenwiderständen, reduziert werden, wenn anstelle von (optimierten) Mehrfach-Beschichtungen Einfach-Beschichtungen mit einer schnelleren Ziehgeschwindigkeit anhand des Dip-Coating-Verfahrens hergestellt wurden. Mit einer klassischen Sol-Gel-ITO-Einfach-Beschichtung, die mit einer deutlich erhöhten Ziehgeschwindigkeit von 600 mm/min gedippt wurde, konnte mit einem Wert von 0.17 der kleinste Gesamtemissionsgrad dieser Arbeit erzielt werden. Die Gesamtemissionsgrade und elektrischen Flächenwiderstände von klassischen Sol-Gel-AZOFunktionsschichten konnten mit dem in dieser Arbeit optimierten Endheizprozess deutlich gesenkt werden. Bei Neunfach-AZO-Beschichtungen konnten der Gesamtemissionsgrad um 0.34 auf 0.50 und der elektrische Flächenwiderstand um knapp 89 % auf 65 Ω/sq verringert werden. Anhand von Hall-Messungen konnte darüber hinaus nachgewiesen werden, dass mit dem optimierten Endheizprozess, der eine erhöhte Temperatur während der Reduzierung der Schichten aufweist, mit N = 4.3·1019 cm-3 eine etwa doppelt so hohe Ladungsträgerdichte und mit µ = 18.7 cm2/Vs eine etwa drei Mal so große Beweglichkeit in den Schichten generiert wurden, im Vergleich zu jenen Schichten, die nach dem alten Endheizprozess ausgehärtet wurden. Das deutet darauf hin, dass bei dem optimierten Heizschema sowohl mehr Sauerstofffehlstellen und damit eine höhere Ladungsträgerdichte als auch Funktionsschichten mit einem höheren Kristallisationsgrad und damit einhergehend einer höheren Beweglichkeit ausgebildet werden. Ein Großteil der vorliegenden Arbeit behandelt die Optimierung und Charakterisierung von ITO-Nanopartikel-Solen bzw. -Funktionsschichten. Neben den verwendeten Nanopartikeln, dem Dispergierungsprozess, der Beschichtungsart sowie der jeweiligen Beschichtungsparameter und der Nachbehandlung der Funktionsschichten, wurde erstmals in einer ausführlichen Parameterstudie die Sol-Zusammensetzung im Hinblick auf die Optimierung der infrarot-optischen und elektrischen Eigenschaften der applizierten Funktionsschichten untersucht. Dabei wurde insbesondere der Einfluss der verwendeten Stabilisatoren sowie der verwendeten Lösungsmittel auf die Schichteigenschaften charakterisiert. Im Rahmen dieser Arbeit wird dargelegt, dass die exakte Zusammensetzung der Nanopartikel-Sole einen große Rolle spielt und die Wahl des verwendeten Lösungsmittels im Sol einen größeren Einfluss auf den Gesamtemissionsgrad und die elektrischen Flächenwiderstände der applizierten Schichten hat als die Wahl des verwendeten Stabilisators. Allerdings wird auch gezeigt, dass keine pauschalen Aussagen darüber getroffen werden können, welcher Stabilisator oder welches Lösungsmittel in den Nanopartikel-Solen zu Funktionsschichten mit kleinen Gesamtemissionsgraden und elektrischen Flächenwiderständen führt. Stattdessen muss jede einzelne Kombination von verwendetem Stabilisator und Lösungsmittel empirisch getestet werden, da jede Kombination zu Funktionsschichten mit anderen Eigenschaften führt. Zudem konnte im Rahmen dieser Arbeit erstmals stabile AZO-Nanopartikel-Sole über verschiedene Rezepte hergestellt werden. Neben der Optimierung und Charakterisierung von ITO- und AZO- klassischen Sol-Gel- sowie Nanopartikel-Solen und -Funktionsschichten wurden auch die infrarot-optischen Eigenschaften dieser Schichten modelliert, um die optischen Konstanten sowie die Schichtdicken zu bestimmen. Darüber hinaus wurden auch kommerziell erhältliche, gesputterte ITO- und AZO-Funktionsschichten modelliert. Die Reflexionsgrade dieser drei Funktionsschicht-Typen wurden einerseits ausschließlich mit dem Drude-Modell anhand eines selbstgeschriebenen Programmes in Sage modelliert, und andererseits mit einem komplexeren Fit-Modell, welches in der kommerziellen Software SCOUT aus dem erweiterten Drude-Modell, einem Kim-Oszillator sowie dem OJL-Modell aufgebaut wurde. In diesem Fit-Modell werden auch die Einflüsse der Glas-Substrate auf die Reflexionsgrade der applizierten Funktionsschichten berücksichtigt und es können die optischen Konstanten sowie die Dicken der Schichten ermittelt werden. Darüber hinaus wurde im Rahmen dieser Arbeit ein Ellipsometer installiert und geeignete Fit-Modelle entwickelt, anhand derer die Ellipsometer-Messungen ausgewertet und die optischen Konstanten sowie Schichtdicken der präparierten Schichten bestimmt werden können. / The aim of this thesis is on the one hand the synthesis of sol-gel functional layers on the basis of transparent conducting oxides (TCOs) and on the other hand a comprehensive infrared-optical and electrical characterization as well as modeling of these layers. Spectrally selective coatings have been prepared with the classical sol-gel route as well as with redispersed nanoparticle sols on glass and polycarbonate substrates and these coatings should have a reflectance in the infrared spectral range which is as high as possible and therefore a total emittance and an electrical sheet resistance which are as small as possible. For this purpose tin doped indium oxide (ITO) and aluminum doped zinc oxide (AZO) have been used as doped metal oxides. Within this thesis several parameters have been investigated in-depth which play a decisive role in the preparation of ITO and AZO low emissivity coatings, in order to prepare such coatings with optimized infrared-optical and electrical properties as well as visual transmittances. Besides the composition of the classical sol-gel ITO coating solutions, also the parameters of the coating as well as the heating processes have been characterized and optimized in the manufacture of classical sol-gel ITO and AZO functional layers. As a significant result the total emittance of classical sol-gel ITO functional layers could be reduced by 0.18 to 0.17 while the visual transmittance and electrical sheet resistances stay approximately the same, if just one-layered coatings are applied with a higher withdrawal speed with the dip coating technique instead of (optimized) multi-layered coatings. With a classical sol-gel ITO single coating, which has been produced with a withdrawal speed of 600 mm/min, the smallest total emittance of this work could be realized with 0.17. The total emittances and electrical sheet resistances of classical sol-gel AZO functional layers were reduced drastically in this work by using the optimized final heating process. The total emittance could be reduced by 0.34 to 0.50 and the electrical sheet resistance by 89 % to 65Ω/sq with a coating which consists of nine single layers. On the basis of Hall measurements it has been shown that coatings which were treated with the optimized heating process (which exhibits a higher temperature during the reducing treatment of the coatings) show a higher charge carrier density as well as a higher mobility than those coatings treated with the old heating process. With the optimized heating process the ninelayered coatings exhibit a charge carrier density of N = 4.3·1019 cm-3 which is approximately twice as high and a mobility of µ = 18.7 cm2/Vs which is about three times higher than the values of coatings which have been heated with the old process. This indicates that with the optimized heating process more oxygen vacancies and, associated therewith a higher charge carrier density as well as a higher crystallinity of the layer and thus a higher mobility are generated. One focus of the presented work lies on the optimization and characterization of ITO redispersed nanoparticle sols and functional layers respectively. In addition to the used nanoparticles, the dispersion process, the coating type with the respective coating parameters and post-treatments of the functional layers also a detailed parameter study has been done. This parameter study examined the composition of the nanoparticle sols with a view to the optimization of the infrared-optical and electrical properties of the applied coatings. The coating properties have been studied in particularly with regard to the influence of the used stabilizers and solvents respectively. In this work it will be shown, that the accurate composition of the nanoparticle sols plays a decisive role and the choice of the used solvents has a bigger impact on the coating properties than the choice of the used stabilizers. However, it will also be shown, that no general statements can be made which stabilizers or which solvents within the sols lead to coatings which have small total emittances and small electrical sheet resistances. Instead each combination of used stabilizer and used solvent has to be empirically tested since each combination leads to coatings with different properties. Furthermore stable AZO nanoparticle sols based on several formulas have been developed for the first time. Besides the optimization and characterization of ITO and AZO classical sol-gel as well as nanoparticle sols and functional layers, also the infrared-optical properties of these coatings have been modeled in order to determine the optical constants as well as the coating thicknesses. Furthermore also commercially available sputtered ITO and AZO coatings have been modeled. The reflectances of these three types of coatings have been modeled on the one hand by using only the Drude model within a self-written program in the software Sage. On the other hand these coatings have been modeled with more complex fitting models within the commercially available software called SCOUT. These more complex fitting models consist of the extended Drude model, a Kim oscillator and an OJL model and they also take the influence of the glass substrates on the reflectances of the applied coatings into account. By using these fitting models, the optical constants of the applied coatings and the coating thicknesses can be obtained. In addition an Ellipsometer has been installed as part of this work and suitable fitting models have been developed. These models can be used for analyzing the Ellipsometer measurements in order to determine the optical constants and the coating thicknesses of the coatings applied.

Sample preparation is a key step in chemical analysis, and includes isolation of target analytes, removal of interferences, preconcentration, and/or modification of target analytes (if needed). Sample preparation is also the most time-consuming and error-prone step in the whole analytical process. Traditional sample preparation techniques involve hazardous solvents. Considering the environmental and health safety, it is desirable to reduce or eliminate organic solvents in sample preparation. Solid phase microextraction (SPME) was introduced as a solvent free sample preparation technique. Capillary microextraction (CME) is one of the formats of SPME that can be easily coupled to high performance liquid chromatography (HPLC). In SPME and CME a solvent free sample preparation is accomplished by using a sorbent coating instead of hazardous organic solvents commonly used in conventional extraction techniques. This research is focused on the development and systematic examination of novel niobia-, titania- and silica-based organic-inorganic hybrid sol-gel sorbents for CME. Conventionally silica and titania based precursors were used in organi-inorganic hybrid sol-gel sorbents for CME, here novel niobia based precursor was used in creating organic-inorganic hybrid sol-gel sorbents. Poly tetrahydrofuran (polyTHF) as well as electrically neutral and charged organic ligands were used to prepare the sorbents for CME coupled to HPLC. Characterization of created sol-gel sorbents, evaluation of extraction performance, and enrichment of environmentally and biomedically important analytes including organophosphorus compounds were performed. CME performances of the created sorbents were characterized by specific extraction (SE) (a measure of extraction efficiency) and desorption efficiency (DE) (a measure of completeness desorption of extracted analytes). Scientific findings of this research has shown that sol-gel niobia-polyTHF sorbent provides 60 to 70 % higher SE values for different environmentally important analytes compared to analogously prepared silica-polyTHF sorbent. This superior extraction performance can be attributed to the presence of surface Lewis acid sites undergoing Lewis acid-base interactions with analytes representing Lewis bases. The prepared sorbents also have the ability to undergo van der Waals interactions due to the presence of polyTHF. Absence of Lewis acid sites on silica surface resulted in inferior extraction efficiency compared to niobia-polyTHF sorbents. Extraction efficiency of the created sol-gel based niobia-polyTHF was also explored in the enrichment of organophosphorus pesticides and compared with that of the state-of-the-art titania-based sorbent. Sol-gel niobia-polyTHF sorbent has provided 40 to 50 % higher SE values in the enrichment of organophosphorus pesticides compared to sol-gel titania-polyTHF sorbent which can be attributed to the presence of bronsted acid sites on niobia surface (but lacking on titania) along with Lewis acid sites. To explore relative contributions of electrostatic, Lewis acid-base and van der Waals interactions between sol-gel sorbents and analytes, two sol-gel sorbents, one containing a positively charged octadecyl ligand and the other a neutral octadecyl ligand were created. Positive charge was imparted by using N-octadecyldimethyl [3-(trimethoxysilyl) propyl] ammonium chloride (C18 (+ve)) as ligand bearing co-precursor. Similarly N-octadecyl trimethoxysilane was used to impart a neutral C18 ligand in sol-gel coating. Experimental results have shown that sol-gel Nb2O5-C18 (+ve) sorbent has superior extraction efficiency compared to sol-gel based Nb2O5-C18 and purely inorganic Nb2O5 sorbents in enrichment of organophosphorus compounds (nucleotides and organophosphorus pesticides). Electrostatic interactions between the positive charge of organic ligand (C18 (+ve)) and negative charge of phosphate group has contributed to the higher extraction performance of sol-gel based Nb2O5-C18 (+ve) sorbent. TiO2-C18 (+ve) sorbent was also created to compare with the novel sol-gel niobia based sorbents, since titania-based sorbents are considered as the state-of-the-art extraction material in the enrichment of organophosphorus compounds. Established research results has shown that sol-gel based Nb2O5-C18 (+ve) sorbent has provided 40 to 50 % higher specific extraction values for organophosphorus compounds compared to sol-gel based TiO2-C18 (+ve) sorbent. Desorption efficiency of sol-gel Nb2O5-C18 (+ve) and TiO2-C18 (+ve) sorbents were 96% vs 90%. This superior DE of sol-gel Nb2O5-C18 (+ve) sorbent can be attributed the higher Lewis acid strength of titania than nioiba. The developed sol-gel niobia based sorbents have also shown high pH stability compared to traditional sol-gel silica based sorbents. The created sol-gel sorbents were characterized by less than 5% run to run RSD values and also less than 5% capillary to capillary RSD values which indicated the high reproducibility of developed method. The developed sol-gel niobia sorbents are applicable to sample preparation in different fields including biomedical, environmental, forensic, defense etc.

Titania-based photocatalysts have been extensively studied for the oxidative photodestruction of organic pollutants in wastewaters, releasing non-toxic substances such as CO2, HCl, and water. However, commercial exploitation of this process is limited by the fact that titania is only active under UV irradiation (wavelength below about 388 nm), which is only less than 5% of solar light energy. Sol-gel synthesised catalyst specimens were characterised to determine the correlation between preparation conditions on morphology (XRD, SEM), optical (bandgap energy level) and physicochemical properties (BET surface area, pore volume, acid site density, acid site strength and type) of the photocatalysts. These spesific properties would then be linked to their photoactivity using aqueous aliphatic and aromatic model pollutants. This study has demonstrated that sol-gel synthesised doped titania photocatalysts, especially Pt/TiO2, may be used to effectively degrade non-volatile acids (DL-malic acid, dichloroacetic acid, and p-hydroxybenzoic acid) under visible light and UV irradiation with significant photoactivity suitable for the solar light application of photocatalytic wastewater treatment. A significant drop in band-gap energy was found for all titania sol-gel catalysts doped with Pt, Co, and Ce with values between 1.41 to 1.78 eV. The BET areas of the photocatalysts were also higher (65-117 m2/g) than that of Degussa P25 (50 m2/g). The visible-light photomineralisation of the three pollutants with Pt-TiO2 specimen were further extended to evaluate the effects of major variables in a bubble-column photoreactor on the photodegradation activities. Those major variables were lamp intensity, oxygen concentration, initial pH, catalyst dosage, and inital pollutant concentration. All the three pollutants seemed to follow the Langmuir-Hinselwood model with dual adsorption sites which implicated a bimolecular surface rate-limiting step probably between the adsorbed organic substrate and a surface hydroxyl (or peroxy) radical. A study of the CeyCoxTi(1-x)O3+d perovskite was conducted to investigate the influence of metal composition and pH on the intrinsic optophysical attributes as well as p-hydroxybenzoic acid degradation under UV irradiation. The perovskite UV photoactivities were lower than that of pure TiO2 likely due to excessive loading (metal content) creating new oxide phases act as electron-hole recombination center, regardless better physicochemical attributes of some of the perovskite samples. The role of aging time and calcination temperature on the sol-gel synthesised TiO2 was also explored. Higher calcination temperature (from 250 to 700 0C) resulted in TiO2 photocatalysts with better crystallinity, which is important for OH group formation as active sites for photodegradation. Despite of some advantages from higher temperature preparation, some detrimental effects such as decreased acidity attributes, surface area, and pore volume were also observed. The significant red-shift of sol-gel synthesized TiO2 into visible light, especially for 250 0C specimen since 600 or 700 0C had extremely low activities, has promising implications that this specimen might be used for solar application to substitute Pt-doped TiO2 in order to produce a more cost effective photocatalyst. Aging period (1 to 14 days) did not have any discernible effect on the band-gap value and acid-site density. Even so, the highest acid site strength was obtained with an aging time of 10 days. From the overall perspective, aging time longer than 3 days did not bring noticeable benefits to both catalyst attributes and photoactivities.

Quantum dots (QDs) of II-VI semiconductors (CdS, CdSe, and CdTe) in the size range of 1~12 nm have attracted great interest in both fundamental research and technical applications in recent years. Due to their tunable size-dependent emission with high photoluminescence quantum yields, their broad excitation spectra and narrow emission bandwidths, the semiconductor QDs have been intensively investigated in versatile applications, including thin-film light emitting devices (LEDs), low-threshold lasers, optical amplifier media for telecommunication networks and biological labels. Thus, constructing and fabricating highly ordered QDs are of great importance in the field of nanotechnology. The surface chemistry behavior of the TOPO-CdSe QDs and TOPO-(CdSe)ZnS QDs at the air-water interface was carefully examined by various physical measurements. The surface pressure-area isotherms of the Langmuir monolayers of both types of QDs gave the average diameter which matched the value determined by TEM measurements. Topographic study of the Langmuir monolayers of both QDs revealed the 2D aggregation during the early stage of the compression process. The stability of the Langmuir monolayer of the TOPO-(CdSe)ZnS QDs was measured by the compression/decompression cycle and the kinetic measurements, both of which indicated that TOPO capped (CdSe)ZnS QDs can form stable Langmuir monolayers at the air-water interface. Langmuir-Blodgett (LB) film of the TOPO-(CdSe)ZnS QDs were prepared on quartz slides at different surface pressures and characterized by photoluminescence (PL) spectroscopy. The linear increase of the PL intensity with the increase of the number of layers deposited onto the quartz slide implied a homogeneous deposition of the Langmuir monolayer. The conjugates of 10, 12-pentacosadiynoic acid (PDA) and short chain peptide was used to modify the surface of (CdSe)ZnS core-shell QDs. The PDA-peptide capped QDs formed stable Langmuir monolayer. After the photopolymerization of PDA-peptide-QDs/PDA-peptide system at the air-water interface, a more uniform and robust Langmuir monolayer was constructed. The 3-mercaptopropyltrimethoxysilane (MPS) was linked to (CdSe)ZnS QDs by ligand exchange method. The sol-gel process of the MPS capped QDs Langmuir monolayer was studied under various subphases of pH and reaction time. The fast sol-gel process under a subphase of pH 12.0 led the formation of a more homogeneous Langmuir monolayer. A smooth MPS-QDs LB film deposited under pH 12.0 was also observed by AFM measurements. The imaging of the aggregates of lysozyme using lysozyme/(CdSe)ZnS QDs conjugate as a PL label was investigated. The amyloid fibrils formed by lysozyme/lysozyme-QDs conjugate were observed by epifluorescence microscopy, atomic force microscopy (AFM) and transmission electron microscopy (TEM) measurements. The emission intensity of the QDs labeled lysozyme was increased about 3 fold after formation of amyloid. This approach, for the first time, provided a convenience method to image the amyloid fibrils by epifluorescence microscopy.

This dissertation presents the synthesis of a series of thermo- and pH-sensitive hydrophilic block copolymers and the study of their solution behavior in water. By incorporating a small amount of weak acid or base groups into the thermosensitive block(s) of a hydrophilic block copolymer, the LCST of the thermosensitive block(s) can be modified by changing the solution pH. Accordingly, the critical micellization temperature (CMT) and the sol-gel transition temperature (Tsol-gel) of the block copolymer in water can be tuned. Chapter 1 describes the synthesis of thermo- and pH-sensitive poly(methoxydi(ethylene glycol) methacrylate-co-methacrylic acid)-b-PEO-bpoly( methoxydi(ethylene glycol) methacrylate co-methacrylic acid) and the study of sol-gel transitions of its aqueous solutions at various pH values. The CMT of the 0.2 wt% solution and the Tsol-gel of the 12.0 wt% solution of this copolymer can be varied over a large temperature range. By judiciously controlling temperature and pH, multiple sol-gel-sol transitions were realized. Chapter 2 presents a systematic study of pH effect on rheological properties of micellar gels formed from 10.0 wt% aqueous solutions of thermo- and pH-sensitive poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid)-b-PEO-b-poly(ethoxydi(ethylene glycol) acrylate-co-acrylic acid). With the increase of pH, the sol-gel transition became broader. The plateau moduli (GN) evaluated from frequency sweeps at T/Tsol-gel of 1.025, 1.032, and 1.039 decreased with the increase of pH from 3.00 to 5.40 with the largest drop observed at pH = ~ 4.7. The decrease in GN reflects the reduction of the number of bridging chains. The ionization of carboxylic acid introduced charges onto the thermosensitive blocks and made the polymer more hydrophilic, facilitating the formation of loops and dangling chains. Chapter 3 presents the synthesis of PEO-b-poly(methoxydi(ethylene glycol)methacrylate-co-2-(N-methyl-N-(4-pyridyl)amino)ethyl methacrylate) with the thermosensitive block containing a catalytic 4-N,N-dialkylaminopyridine and the study of the effect of thermo-induced micellization on its activity in the hydrolysis of pnitrophenyl acetate. The CMTs of this copolymer at pH of 7.06 and 7.56 were 40 and 37 °C, respectively. Below CMT, the logarithm of initial hydrolysis rate changed linearly with 1/T. Above CMT, the reaction rate leveled off, which is presumably because it was controlled by mass transport to the core of micelles above CMT.

The present work analyses the physicochemical phenomena responsible for the microstructure of Pd/SiO2 xerogel catalysts and of metal-free hybrid SiO2 xerogels synthesized by sol-gel process. The samples are synthesized by co-polymerizing tetraethoxysilane (TEOS) with 3-aminopropyltriethoxysilane or 3-(2-aminoethylamino)propyltrimethoxysilane in ethanol, the latter co-reactant possibly forming a complex with palladium. The analysis is conducted by following in situ the formation of the gels' nanostructure by Small-Angle X-ray Scattering (SAXS), by characterizing the microstructure of the final gels by beam-bending, and by analyzing the microstructure of the xerogels after desiccation, most notably by electron tomography. The in situ SAXS analysis shows that the nanometer structure of the gels forms via a reaction-induced phase separation. The microstructure of the hybrid xerogels is hierarchical, as assessed by electron microscopy, nitrogen adsorption and SAXS. Its structure is that of a microcellular foam at large scale, with pores a few hundred nanometers across, supported by elongated filaments, a few ten nanometers wide, each filament being made up by smaller structures, a few nanometers wide. The characteristics of the various structural levels depend on the nature and concentration of the co-reactant used. In the case of xerogel catalysts, electron tomography shows that Pd nanoparticles are regularly dispersed inside the silica, with distances between them comparable to the thickness of the skeleton. On the basis of the time-resolved SAXS and of the characterization of the xerogels, it is argued that a double phase separation process is responsible for the structuring of the gels, with a primary phase separation leading to the microcellular foam morphology, and a secondary phase separation being responsible for the substructure of the filaments. The large scale structure of the gels themselves, before desiccation, is analyzed by beam bending. This enables one to estimate the mechanical properties of the gels as well as the size of their largest pores. The microstructure of aerogels obtained by supercritical drying of the samples is also investigated. The comparison of the characterization data show that the nature and concentration of the co-reactant controls the amount of shrinkage that the gels undergo during desiccation, at the macroscopic scale as well as at the scale of the filaments.

Fuel cell technologies have developed high interest due to their ability to provide energy in an environmentally friendly method. Proton exchange membrane fuel cells (PEM-FCs) require a PEM for use, where the most accepted PEM used today is Nafion. Nafion is ideal due to its chemical durability and high proton conductivity however it is highly expensive and limited to 80˚C during operation. To target these issues two methods have been developed. One was to synthesize a new membrane material to replace Nafion based upon sulphonated polysiloxanes and the other was to improve Nafion by synthesizing a composite. Both of these methods involved the sulphonated silane 2-4-chlorosulphonylphenethyltrimethoxysilane. Methods to characterize membranes to observe their properties compared to Nafion were thermogravimetric analysis (TGA), Fourier transmission infrared spectroscopy (FT-IR), electrochemical impedance spectroscopy (used to determine proton conductivity) and fuel cell performance. / UOIT

Sol-gel (solution-gelation) method was used to prepare Ni-Ti and Ni-Ti-Al catalysts for reforming of methane with carbon dioxide. This method, after optimizing the parameters such as hydrolysis and acid/alkoxide ratio, is able to make a Ni-Ti catalyst with a surface area as high as 426m2/g when calcined at 473K; but calcination at higher temperature lead to dramatic decrease in surface area. XRD, XPS, TEM and SEM were used to understand this change. Using a packed bed reactor, the catalysts were evaluated with the reforming reaction. It was found that the activity of the Ni-Ti catalyst increases with the Ni loading in the range of 1-10wt%. The reduction temperature has strong effect on activity of the reduced catalyst. Up to 973K, the activity increases with the reduction temperature; but after 973K, the activity decreases and become 0 when the temperature is over 1023K. The Ni-Ti catalyst also deactivated as 15% after 4h of time on stream. The XRD analysis shows that Ti3O5 formed in the catalyst after higher-temperature reduction as well as after the reaction for a period of time. The formation of Ti3O5 may render the catalyst to loss its activity. However, further study is expected to understand the mechanism. TG/DTA analysis shows that both Ni-Ti and Ni-Ti-Al catalysts had carbon deposition; but the latter maintained higher activity in a longer period of time.

No description available.

La present Tesi Doctoral es basa en la preparació, caracterització i assaig de catalitzadors suportats. Els materials preparats són híbrids orgànico-inorgànics derivats de silici. S'han utilitzat diferents mètodes de preparació, principalment el procés sol-gel. En primer lloc, s'han obtingut materials derivats d'un complex de Pd de tipus bipiridínic que s'han utilitzat com a catalitzadors en reaccions de Suzuki, Heck i Sonogashira, mostrant una elevada activitat i un bon reciclatge. També s'han sintetitzat materials derivats de sals d'imidazoli i de dihidroimidazoli que ens han permès, per una banda, preparar complexos de Ru suportats derivats de catalitzadors de Grubbs. Aquests catalitzadors s'han assajat en reaccions de ring closing metathesis de diens i enins. L'activitat i el reciclatge en aquest cas van ser baixos. Els mateixos híbrids orgànico-inorgànics, juntament amb Pd(OAc)2, s'han assajat en reaccions de Suzuki, Heck i Sonogashira, amb una bona activitat i s'han pogut reutilitzar. Finalment, aquests materials han resultat ser actius i reciclables com a organocatalitzadors en condensacions de Knoevenagel. Amb els lligands bi- i trisililats derivats de sals d'imidazoli amb cadenes hidrocarbonades llargues s'ha estudiat l'autoestructuració de materials híbrids orgànico-inorgànics. Algunes de les sals d'imidazoli no sililades que s'han sintetitzat han resultat ser cristalls líquids iònics. S'han estudiat les seves propietats mesomòrfiques i les seves possibles aplicacions. / The present Doctoral Thesis is based on the preparation, characterization and assay of supported catalysts. We focused on organic-inorganic hybrid silica materials. Different methods have been used in the preparation of these materials, mainly the sol-gel process. Firstly, materials derived from a bipyridinic Pd complex have been obtained which have been tested as catalysts in Suzuki, Heck and Sonogashira reactions, showing a high activity and a good recycling. Materials derived from imidazolium and dihydroimidazolium salts have been also synthesized which serve us to prepare Ru supported complexes derived from Grubbs catalysts. These catalysts have been tested in diene and enyne ring closing metathesis reactions. The activity and recycling in this case was low. The same organic-inorganic hybrid materials, with Pd(OAc)2, have been tested in Suzuki, Heck and Sonogashira reactions, with a good activity and they have been reused. Finally, these materials were active and recyclable as organocatalysts in Knoevenagel condensations. The self-structuration of new organic-inorganic hybrid materials prepared with bis- and trisilylated ligands derived from imidazolium salts with long hydrocarbonated chains have been studied. Some of the non-silylated imidazolium salts were ionic liquid crystals. Their mesomorphic properties and their possible applications have been studied.