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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

A Radical Approach to Syntheses and Mechanisms

Hancock, Amber N. 24 October 2011 (has links)
The critically important nature of radical and radical ion mechanisms in biology and chemistry continues to be recognized as our understanding of these unique transient species grows. The work presented herein demonstrates the versatility of kinetic studies for understanding the elementary chemical reactions of radicals and radical ions. Chapter 2 discusses the use of direct ultrafast kinetics techniques for investigation of crucially important enzymatic systems; while Chapter 3 demonstrates the value of indirect competition kinetics techniques for development of synthetic methodologies for commercially valuable classes of compounds. The mechanism of decay for aminyl radical cations has received considerable attention because of their suspected role as intermediates in the oxidation of tertiary amines by monoamine oxygenases and the cytochrome P450 family of enzymes. Radical cations are believed to undergo deprotonation as a key step in catalysis. KIE studies performed by previous researchers indicate N,N-dimethylaniline radical cations deprotonate in the presence of the bases acetate and pyridine. By studying the electrochemical kinetics of the reaction of para substituted N,N-dimethylaniline radical cations with acetate anion, we have produced compelling evidence to the contrary. Rather than deprotonation, acetate reacts with N,N-dimethylaniline radical cation by electron transfer, generating the neutral amine and acetoxyl radical. Transport properties of reactants and solvent polarity changes were investigated and confirmed not to influence the electrochemical behavior forming the basis for our mechanistic hypothesis. To reconcile our conclusion with earlier results, KIEs were reinvestigated electrochemically and by nanosecond laser flash photolysis. Rather than a primary isotope effect (associated with C-H bond cleavage), we believe the observed KIEs are secondary, and can be rationalized on the basis of a quantum effect due to hyperconjugative stabilization in aromatic radical cations during an electron transfer reaction. Product studies performed by constant potential coulometry indicate N,N-dimethylaniline radical cations are catalytic in carboxylate oxidations. Collectively, our results suggest that aminyl radical cation deprotonations may not be as facile as was previously thought, and that in some cases, may not occur at all. Interest in design and synthesis of selenium containing heterocycles stems from their ability to function as antioxidants, anti-virals, anti-inflammatories, and immunomodulators. To establish synthetic feasibility of intramolecular homolytic substitution at selenium for preparation of selenocycles, we set out to determine what factors influence cyclization kinetics. A series of photochemically labile Barton and Kim esters have been syntheisized and employed as radical precursors. The effect of leaving radical stability on kinetics has been investigated through determination of rate constants and activation parameters for intramolecular homolytic substitution of the corresponding radicals via competition experiments. Notable leaving group effects on measured kinetic parameters show more facile reactions for radical precursors with more stable leaving radicals. Moreover, cyclizations to form six-membered (as opposed to five- membered) ring systems exhibited order of magnitude decreases in rate constants for a given leaving radical. Our results are congruent with expectations for radical cyclizations trends for the varied experimental parameters and suggest homolytic substitution affords a convenient means for synthesis of selenocycles. / Ph. D.
42

Monte Carlo simulation of the radiolysis of water by fast neutrons at elevated temperatures up to 350°C / Simulation Monte Carlo de la radiolyse de l'eau par des neutrons rapides à températures élevées allant jusqu'à 350°c

Butarbutar, Sofia Loren January 2014 (has links)
Résumé : Le contrôle de la chimie de l'eau dans un réacteur nucléaire refroidi à l'eau nécessite une compréhension détaillée des effets de la radiolysede l'eau afin de limiter la corrosion et la dégradation des matériaux par oxydation générée par les produits de cette radiolyse. Toutefois, la mesure directe de la chimie dans le cœur des réacteurs est extrêmement difficile, sinon impossible, en raison des conditions extrêmes de haute température et haute pression, et les champs d’irradiation mixtes neutrons/γ, qui ne sont pas compatibles avec l'instrumentation chimique normale. Pour ces raisons,des modèles théoriques et des simulations sur ordinateur sont essentielles pour la prédiction de la chimie sous rayonnement de l'eau de refroidissement dans le cœur et son impact sur les matériaux. Dans ce travail, des simulations Monte Carlo ont été utilisées pour calculer les rendements des principales espèces (e[indice supérieur -][indice inférieur aq], H[indice supérieur •], H[indice inférieur 2], [indice supérieur •]OH et H[indice inférieur 2]O[indice inférieur 2]) formées lors de la radiolyse de l’eau liquide neutre par des neutrons mono-énergétiques de 2 MeV à des températures entre 25 et 350 °C. Le choix des neutrons de 2 MeV comme énergie d'intérêt est représentatif du flux de neutrons rapides dans un réacteur. Pour l'eau légère, la contribution la plus significative à la radiolyse vient des quatre premières collisions des neutrons qui produisent, dans la majorité des cas, des protons avec des énergies de recul de ~1.264, 0.465, 0.171 et 0.063 MeV et des transferts d’énergie linéique (TEL) moyens respectivement de ~22, 43, 69et 76 keV/[micro]m. Par ailleurs, nous avons négligé les effets des radiations dus aux ions de recul de l’oxygène. Les rendements moyens finaux peuvent alors être estimés comme étant la somme des rendements résultant de l’action de ces protons après pondérations en fonction de l’énergie déposée. Les rendements ont été calculés à 10[indice supérieur -7], 10[indice supérieur -6] et 10[indice supérieur -5] s. Les valeurs obtenues sont en accord avec les données expérimentales disponibles. En comparant nos résultats avec les données obtenues pour les rayonnements à faible TEL (rayons γ de [indice supérieur 60]Co ou électrons rapides), nos rendements calculés pour les neutrons rapides ont montré une dépendance en température essentiellement similaire, mais avec des valeurs plus faibles pour les rendements en radicaux libres et des valeurs plus élevées pour les rendements moléculaires. Nous avons également utilisé les simulations Monte Carlo pour étudier l'existence de la chute rapide de la constante de vitesse de réaction de l'électron hydraté (e[indice supérieur -][indice inférieur aq]) sur lui-même – l’une des principales sources de formation de H[indice inférieur 2] – au-dessus de 150 °C. Cette dépendance en température a été observée expérimentalement en milieu alcalin par divers auteurs, mais jamais en milieu neutre. Lorsque cette baisse de la constante de vitesse d’auto-réaction de e[indice supérieur -][indice inférieur aq] est incluse dans nos codes de simulation, tant pour des rayonnements de bas TEL (grappes isolés) que de haut TEL (trajectoires cylindriques), g(H[indice inférieur 2]) montre une discontinuité marquée à la baisse à ~150°C, ce qui n'est pas observée expérimentalement. Les conséquences de la présence de cette discontinuité dans le rendement en H[indice inférieur 2] pour les rayonnements à bas et haut TEL sont discutées. Enfin, nous avons tenté d’expliquer l'augmentation – considérée comme anormale – du rendement en H[indice inférieur 2] en fonction de la température au-dessus de 200 °C par l’intervention de la réaction des atomes H[indice supérieur •] avec l'eau, préalablement proposée par Swiatła-Wojcik et Buxton en 2005. La constante de vitesse de cette réaction est toujours controversée. // Abstract : Controlling the water chemistry in a water-cooled nuclear power reactor requires understanding and mitigating the effects of water radiolysis to limit the corrosion and degradation of materials by oxidizing radiolysis products. However, direct measurement of the chemistry in reactor cores is extremely difficult due to the extreme conditions of high temperature, pressure, and mixed neutron/γ-radiation fields, which are not compatible with normal chemical instrumentation. For these reasons, theoretical models and computer simulations are essential for predicting the detailed radiation chemistry of the cooling water in the core and the impact on materials. Monte Carlo simulations were used to calculate the yields for the primary species (e[superscript -][subscript aq], H[superscript •], H[subscript 2], [superscript •]OH, and H[subscript 2]O[subscript 2]) formed from the radiolysis of neutral liquid water by mono-energetic 2-MeV neutrons and the mechanisms involved at temperatures between 25 and 350 °C. In this work, we chose 2-MeV neutron as our energy of interest since it is known as representative of a fast neutron flux in a nuclear reactor. For light water, for that chosen energy, the most significant contribution to the radiolysis comes from the first four neutron collisions that generate mostly ejected protons with energies of ~1.264, 0.465, 0.171, and 0.063 MeV, which had, at 25 °C, mean linear energy transfers (LETs) of ~22, 43, 69, and 76 keV/[micro]m, respectively. In this work, we simply neglected the radiation effects due to oxygen ion recoils. The average final fast neutron yields could be estimated as the sum of the yields for these protons after allowance was made for the appropriate weightings (by using the Eq (2) in Chapter 4) according to their deposited energy. Yields were calculated at 10[superscript -7], 10[superscript -6] and 10[superscript -5] s. Our computed yield agreed reasonably well with the available experimental data. By comparing our results with data obtained for low-LET radiation ([superscript 60]Co γ-rays or fast electrons), our computed yields for fast neutron radiation showed essentially similar temperature dependences over the range of temperature studied, but with lower values for yields of free radicals and higher values for molecular yields. In this work, we also used our Monte Carlo simulation to investigate the existence of drop of hydrated electron (e[superscript -][subscript aq]) self-reaction rate constant at 150 °C. One of the main sources of H[subscript 2] formation is the self-reaction of hydrated electrons. The temperature dependence of the rate constant of this reaction (k[subscript 1]), measured under alkaline conditions, reveals that the rate constant drops abruptly above ~150 °C. However, when this drop in the e[superscript -][subscript aq] self-reaction rate constant is included in our code for low (isolated spurs) and high (cylindrical tracks) linear energy transfer (LET), g(H[subscript 2]) shows a marked downward discontinuity at ~150 °C which is not observed experimentally. The consequences of the presence of this discontinuity in H[subscript 2] yield for both low and high LET radiation are discussed. Another reaction that might explain the anomalous increasing of H[subscript 2] yield with temperature is the reaction of H[superscript •] atoms with water previously proposed by Swiatla-Wojcik and Buxton (2005) whose rate constant is still in controversial.
43

Performance evaluation of pilot-scale constructed wetlands for the treatment of domestic wastewater in Addis Ababa, Ethiopia

Belachew, Mengesha Dagne 06 1900 (has links)
An experimental study was carried out to evaluate the performance of pilot scale constructed wetlands for the treatment of domestic wastewater in Addis Ababa, Ethiopia. Three parallel sets of constructed wetlands; consisting of one Horizontal Flow (HF), one Vertical Flow (VF) and one hybrid of HF and VFconstructed in series were built in Addis Ababa. The wetland systems had identical wetland fill media and macrophytes but with different wastewater flow types. The total surface area of the wetland systems was 72 m2 /24 m2 for each/ and designed to treat 3.15 m3 of domestic wastewater per day. Triplicate grab samples were taken from the influent and effluents every 15 days for one year and analyzed within 24 hours. Temperature, pH, DO and EC were measured onsite and the nutrient content of macrophytes was determined twice during the monitoring period. During the first 12 months monitoring period, the average removal efficiencies of the HFCW, VFCW and hybrid CW were: BOD (89.1%, 92.2% and 93.4%), COD (80.6%, 82.1% and 84.0%), TSS (89.1, 83.8% and 84.7%), NH4 + (58.6%, 66.2% and 65.4%), NO3 - (64.0%, 71.5% and 73.5%), TN (49.1%, 54.9% and 58.7%), PO4 3- (45.4%, 50.3% and 48.4%), TP (58.0%, 51.7% and 54.4%) and FC (98.6%, 96.6% and 96.5%), respectively. The hybrid system showed relatively higher removal efficiencies for most pollutants. Again, the wetland systems showed relatively higher percent reduction during the dry seasons /from Dec - May/. The areal removal rate constants of BOD5, TN, PO4 3- and TP were higher than the literature values while the values of COD and TSS were lower compared to the literature values. Concerning the nutrient content of the wetland plant, the average TN contents of the below-ground and above-ground plant part were 1.56% and 2.27% for the HFCW, 1.75% and 2.74% for the VFCW and 1.80% and 2.63% for the hybrid system, respectively. Meanwhile, the average TP contents of the belowground and above-ground plant part were 0.139% and 0.064% for the HFCW, 0.167% and 0.067% for the VFCW and 0.115% and 0.065% for the hybrid systems, respectively. In general, the results showed that properly designed constructed wetland systems could be used as effective wastewater treatment method in Ethiopia. / Environmental Sciences / Ph. D. (Environmental Sciences)
44

Application of diffusion laws to composting: theory, implications, and experimental testing

Chapman, P. D. January 2008 (has links)
Understanding the fundamentals of composting science from a pragmatic perspective of necessity involves mixtures of different sizes and types of particles in constantly changing environmental conditions, in particular temperature. The complexity of composting is affected by this environmental variation. With so much "noise" in the system, a question arises as to the need to understand the detail of this complexity as understanding any part of composting with more precision than this level of noise is not likely to result in greater understanding of the system. Yet some compost piles generate offensive odours while others don‟t and science should be able to explain this difference. A driver for this research was greater understanding of potential odour, which is assumed to arise from the anaerobic core of a composting particle. It follows that the size of this anaerobic core could be used as an indicator of odour potential. A first step in this understanding is the need to determine which parts of a composting particle are aerobic, from which the anaerobic proportion can be determined by difference. To this end, this thesis uses a finite volume method of analysis to determine the distribution of oxygen at sub-particle scales. Diffusion laws were used to determine the thickness of each finite volume. The resulting model, called micro-environment analysis, was applied to a composting particle to enable determination of onion ring type volumes of compost (called micro-environments) containing substrates (further subdivided into substrate fractions) whose concentrations could be determined to high precision by the application of first-order degradation kinetics to each of these finite volumes. Determination of the oxygen concentration at a micro-environment's inner boundary was achieved by using the Stępniewski equation. The Stępniewski model was derived originally for application to soil aeration and enables each micro-environment to have its own oxygen uptake rate and diffusion coefficient. This first version of micro-environment analysis was derived from the simpler solution to diffusion laws, based on the assumption of non-diffusible substrate. It was tested against three sets of experimental data with two different substrates: Particle size trials using dog sausage as substrate – where the peak composting rate was successfully predicted, as a function of particle size. Temperature trials using pig faeces and a range of particle sizes – the results showed the potential of micro-environment analysis to identify intriguing temperature effects, in particular, a different temperature effect (Q10) and fraction proportion was indicated for each substrate fraction. Smaller particle sizes, and possibly outward diffusion of substrate confounded a clear experimental signal. Diffusion into a pile trials which showed that the time course of particles deeper in the pile could be predicted by the physics of oxygen distribution. A fully computed prediction would need an added level of computational complexity in micro-environment analysis, arising from there being two intertwined phases, gas phase and substrate (particle) phase. Each phase needs its own micro-environment calculations which can not be done in isolation from each other. Unexplainable parts of the composting time course are likely to be partly explained by the outward diffusion of substrate towards the inward-moving oxygen front. Although the possibility of alternative electron acceptors can not be discounted as a partial explanation. To test the theory, a new experimental reactor was developed using calorimetry. With an absolute sensitivity of 0.132 J hr-1 L-1 and a measurement frequency of 30 minutes, the reactor was able to detect the energy required to humidify the input air, and "see" when composting begins to decline as oxygen is consumed. Optimisation of the aeration pumping frequency using the evidence from the data was strikingly apparent immediately after setting the optimum frequency. Micro-environment analysis provides a framework by which several physical effects can be incorporated into compost science.
45

Kinetic Studies Of The Thermolysis Of 3-Halogenated-4,5-Dihydro-3h-Pyrazoles

Desalegn, Nebiyou 12 May 2005 (has links)
3-Chloro-4,4,5-trimethyl-3,5-diphenyl-4,5-dihydro-3H-pyrazole (3b) and 3-bromo-4,4,5-trimethyl-3,5-diphenyl-4,5-dihydro-3H-pyrazole (3c) were prepared for the thermolysis project. The thermal decompositions of 3b and 3c were monitored using 1H NMR spectroscopy. Plots of ln (% starting material) vs. time (sec) were linear for at least two half lives and the first order rate constants were determined over at least a 30o temperature range. The relative reactivity was found to be 3c > 3b. The activation parameters determined for the thermal decomposition of the pyrazoline at 150oC were found to be: for 3b &#;H‡ = 33 &#;1.0 kcal/mol, &#;S‡ = -2.4 &#; 0.07eu , k150 0 = 7.34 &#; 0.44 x 10 -5 s-1 ; for 3c &#;H‡ = 30&#;0.2 kcal/mol, &#;S‡ = -6.9 &#;0.03 eu, k150o = 42.3&#;0.7 x 10-5 s-1. Thermal decomposition of 3b both neat and in dibromobenzene (DBB) resulted in the formation of an intermediate 2,3-diphenyl-4-methyl-1,3-pentadiene (8) as a major product and minor isomers of 8. These intermediates then thermally decomposed to 1,1,3-trimethyl-2-phenyl-1H-indene (9) via an acid catalyzed process. In order to gain a mechanistic understanding (ionic vs. radical pathways) of the thermal decomposition of 3b, a product study was conducted in protic solvents. In methanol and ethanol, 3b underwent an ionic reaction (SN1-type) with the solvent to produce 3-methoxy/ethoxy-4,4,5-trimethyl-3,5-diphenyl-4,5-dihydro-3H-pyrazole (3/3d) in good yield. The reaction of 3b with refluxing protic solvents led to the development of new method for the synthesis of alkoxy-4,5-dihydro-3H-pyrazoles which is both safe and efficient.
46

Modelling and elucidation of photoreaction kinetics : applications and actinometry using nifedipine, nisoldipine, montelukast, fluvoxamine and riboflavin

Maafi, Wassila January 2016 (has links)
The kinetics of drugs photodegradation have traditionally been treated using thermal kinetic analysis methods consisting most commonly in zero and first order kinetics. These treatment strategies were shown to lack specificity and present a number of limitations when applied to photoreactions kinetics. Nevertheless, these methods have widely been used due to a lack of integrated rate-laws for the majority of photoreactions types, in turn, due to the presence of a variable time-dependent factor in most photoreactions rate-laws that prevents their mathematical integration. To address these limitations, a new methodology for the development and validation of semi-empirical integrated rate-laws that faithfully describe photoreactions kinetics and photoreactions simulated cases generated by numerical integration methods (NIMs), is hereby presented. Using this methodology, a new kinetic order was ascribed to photoreactions namely the Φ-order kinetics. Semi-empirical integrated rate-laws were, thus, developed for three photoreaction types namely, unimolecular, AB(1Φ), photoreversible ,AB(2Φ), and consecutive, AB4(4Φ), photoreactions. The proposed models were further tested experimentally on drugs following these photodegradation mechanisms using; nifedipine and nisoldipine for unimolecular photoreactions; montelukast and fluvoxamine for photoreversible reactions; and riboflavin for consecutive photoreactions. The developed models not only accurately described the photoreaction kinetics of these drugs but also allowed the determination of all the kinetic parameters that characterise them. Furthermore, the above studied drugs were shown to act as precise and simple actinometers when analytically treated with the Φ-order kinetic methods, hereby presented. A universal standard method for the precise and worldwide reproducible study of drugs stability and compounds photoreactions, based on monochromatic irradiation and Φ-kinetics data analysis, is also detailed and adopted throughout the thesis. Finally, two new kinetic parameters namely, the pseudo-rate-constant and pseudo-initial velocity have been identified and shown to be more reliable and accurate in the description and universal comparison of photoreactions kinetics.
47

Hydrogen electrochemistry in room temperature ionic liquids

Meng, Yao January 2012 (has links)
This thesis primarily focuses on the electrochemical properties of the H<sub>2</sub>/H<sup>+</sup> redox couple, at various metallic electrodes in room temperature ionic liquids. Initially, a comprehensive overview of room temperature ionic liquids, RTILs, compared to conventional organic solvents is presented which identifies their favourable properties and applications, followed by a second chapter describing the basic theory of electrochemistry. A third chapter presents the general experimental reagents, instruments and measurements used in this thesis. The results presented in this thesis are summarized in six further chapters and shown as follows. (1) Hydrogenolysis, hydrogen loaded palladium electrodes by electrolysis of H[NTf<sub>2</sub>] in a RTIL [C<sub>2</sub>mim][NTf<sub>2</sub>]. (2) Palladium nanoparticle-modified carbon nanotubes for electrochemical hydrogenolysis in RTILs. (3) Electrochemistry of hydrogen in the RTIL [C<sub>2</sub>mim][NTf<sub>2</sub>]: dissolved hydrogen lubricates diffusional transport. (4) The hydrogen evolution reaction in a room temperature ionic liquid: mechanism and electrocatalyst trends. (5) The formal potentials and electrode kinetics of the proton_hydrogen couple in various room temperature ionic liquids. (6) The electroreduction of benzoic acid: voltammetric observation of adsorbed hydrogen at a Platinum microelectrode in room temperature ionic liquids. The first two studies show electrochemically formed adsorbed H atoms at a metallic Pt or Pd surface can be used for clean, efficient, safe electrochemical hydrogenolysis of organic compounds in RTIL media. The next study shows the physicochemical changes of RTIL properties, arising from dissolved hydrogen gas. The last three studies looked at the electrochemical properties of H<sub>2</sub>/H<sup>+</sup> redox couple at various metallic electrodes over a range of RTILs vs a stable Ag/Ag<sup>+</sup> reference couple, using H[NTf<sub>2</sub>] and benzoic acid as proton sources. The kinetic and thermodynamic mechanisms of some reactions or processes are the same in RTILs as in conventional organic or aqueous solvents, but other remarkably different behaviours are presented. Most importantly significant constants are seen for platinum, gold and molybdenum electrodes in term of the mechanism of proton reduction to form hydrogen.
48

Neuartige Radikalische Polymerisation von Vinylmonomeren über eine Iminbase / Isocyanat-vermittelte Initiierung

Polenz, Ingmar 24 February 2012 (has links) (PDF)
Gegenstand dieser Arbeit ist die Entwicklung einer neuartigen Initiierungsmethode zur Polymerisation von Vinylmonomeren über die Kombination von gewöhnlichen organischen Isocyanaten und Iminbasen. Der radikalische Charakter dieses Polymerisationstyps wurde durch Copolymerisationsexperimente verifiziert. Mit verschiedenen Iminbase / Isocyanat-Kombinationen als Initiatoren wurde die Homopolymerisation von diversen (Meth)-Acrylaten, Styrol, Acrylnitril und Methacrylnitril untersucht. Parameter, wie die Brutto-Polymerisationsgeschwindigkeitskonstante und die Aktivierungsenergie wurden ermittelt und Aussagen zur Polymerisation getroffen. Über die Auswertung von Massenspektren niedermolekularer Polymer-Proben wurden Vermutungen zum ablaufenden Initiierungsmechanismus abgeleitet. Das Anwendungspotential dieser Methode wurde in Hinblick auf die Synthese diverser Polymerarchitekturen untersucht. Neben der Oberflächenpolymerisation an funktionalisierten Kieselgel-Partikeln mittels „grafting-from“ wurden neuartige Block- und Kammpolymer-Strukturen hergestellt und analysiert. Zudem wurde die durch reine Iminbasen vermittelte Polymerisation von (Meth-)Acrylaten untersucht. Ferner wird der positive Einfluss der Zugabe katalytischer Mengen Ionischer Flüssigkeiten auf beide Systeme gezeigt und diskutiert.
49

Neuartige Radikalische Polymerisation von Vinylmonomeren über eine Iminbase / Isocyanat-vermittelte Initiierung

Polenz, Ingmar 17 February 2012 (has links)
Gegenstand dieser Arbeit ist die Entwicklung einer neuartigen Initiierungsmethode zur Polymerisation von Vinylmonomeren über die Kombination von gewöhnlichen organischen Isocyanaten und Iminbasen. Der radikalische Charakter dieses Polymerisationstyps wurde durch Copolymerisationsexperimente verifiziert. Mit verschiedenen Iminbase / Isocyanat-Kombinationen als Initiatoren wurde die Homopolymerisation von diversen (Meth)-Acrylaten, Styrol, Acrylnitril und Methacrylnitril untersucht. Parameter, wie die Brutto-Polymerisationsgeschwindigkeitskonstante und die Aktivierungsenergie wurden ermittelt und Aussagen zur Polymerisation getroffen. Über die Auswertung von Massenspektren niedermolekularer Polymer-Proben wurden Vermutungen zum ablaufenden Initiierungsmechanismus abgeleitet. Das Anwendungspotential dieser Methode wurde in Hinblick auf die Synthese diverser Polymerarchitekturen untersucht. Neben der Oberflächenpolymerisation an funktionalisierten Kieselgel-Partikeln mittels „grafting-from“ wurden neuartige Block- und Kammpolymer-Strukturen hergestellt und analysiert. Zudem wurde die durch reine Iminbasen vermittelte Polymerisation von (Meth-)Acrylaten untersucht. Ferner wird der positive Einfluss der Zugabe katalytischer Mengen Ionischer Flüssigkeiten auf beide Systeme gezeigt und diskutiert.:ABKÜRZUNGSVERZEICHNIS 6 1 EINLEITUNG UND AUFGABENSTELLUNG 10 1.1 Einleitung 10 1.2 Motivation und Zielsetzung 13 2 ALLGEMEINER TEIL UND THEORETISCHE GRUNDLAGEN 15 2.1 Grundlagen der freien radikalischen Polymerisation 15 2.2 Atom Transfer Radical Polymerization (ATRP), Reversible Addition-Fragmentation Chain Transfer Polymerization (RAFT) und Nitroxide Mediated Radical Polymerization (NMP) als Beispiele für kontrollierte radikalische Polymerisationen 25 2.3 Theorie zur Copolymerisation von Vinylmonomeren 34 2.4 Applikation von Ionischen Flüssigkeiten bei der radikalischen Polymerisation 43 3 ERGEBNISSE UND DISKUSSION 49 3.1 Iminbase/Isocyanat-vermittelte (IBI) Polymerisation von Vinylmonomeren 49 3.1.1 Empirische Befunde und Klassifizierung der IBI-Systeme 50 3.1.2 Ergebnisse zu den IBI-Polymerisationen mit unmittelbarem Verbrauch der Initiator- Komponenten (Typ A) 58 3.1.3 Verwendung der Iminbase–Isocyanat-Addukte zur Polymerisation von MMA 70 3.1.4 Ergebnisse der Polymerisationen mit Typ B IBI-Kombinationen 78 3.1.5 Bestimmung und Auswertung kinetischer Parameter der IBI-Polymerisation 85 3.1.6 Studien zum Initiierungsmechanismus durch die Iminbase/Isocyanat-Kombination 102 3.2 Iminbasen-(Meth-)Acrylat-induzierte (IBA) Polymerisation 124 3.2.1 Phänomenologische Untersuchungen zur IBA-Polymerisation 124 3.2.2 Kinetik der IBA-Polymerisation und mechanistische Studien 129 3.3 Beschleunigung beider Polymerisationstypen über die Zugabe katalytischer Mengen Ionischer Flüssigkeit 143 3.3.1 Untersuchungen zur Wechselwirkung von Ionischen Flüssigkeit mit den Reaktanden mit Hilfe der ATR-FT-MIR-Spektroskopie 144 3.3.2 Ergebnisse zu den IL-katalysierten IBI-Polymerisationen 151 3.3.3 Ergebnisse zu den IL-katalysierten IBA-Polymerisationen 162 3.4 Applikation der neuartigen Polymerisationssysteme zur Blockcopolymerisation 171 3.4.1 Oberflächenpolymerisation an Siliziumdioxid-Partikeln 172 3.4.2 Blockcopolymer-Synthese mit Typ A IBI-Oligomeren 186 3.4.3 Kammpolymer-Synthese über die Anwendung der IBI- bzw. IBA-Methode 192 4 ZUSAMMENFASSUNG UND AUSBLICK 200 5 EXPERIMENTELLER TEIL 208 5.1 Verwendete Geräte 208 5.2 Verwendete Chemikalien 210 5.3 Details zur Berechnung der Copolymerisationsparameter, Beladungen und Pfropfgrade 210 5.4 Synthesen und Polymerisationen 213 5.4.1 Allgemeine Vorgehensweise und Ergebnisse bei den Homo- und Copolymerisationen 213 5.4.2 Synthese der Iminbase–Isocyanat Addukte 222 5.4.3 Synthese der funktionalisierten Siliziumdioxid-Partikel und deren Oberflächenpolymerisation 236 5.4.4 Abspaltung von kovalent gebundenem PMMA mittels Dimethylsulfat / NaOCH3 242 5.4.5 Vorgehensweise bei der Verwendung der Spritzenpumpen-Apparatur 246 5.4.6 Synthese und Charakterisierung der organischen Blockcopolymere 247 6 LITERATURVERZEICHNIS 253 7 ANHANG 264 7.1 Kristallographische Daten zu den ermittelten Strukturen 264 7.2 Weiterführende Details zu den durchgeführten Konzentrations-Zeit-Beziehungen 278 7.2.1 Iminbase / Isocyanat-vermittelte (IBI) Polymerisation 278 7.2.2 Iminbase-(Meth-)Acrylat-vermittelte (IBA) Polymerisation 302 7.3 Fineman und Ross Beziehungen und Copolymerisationsdiagramme 314 7.4 Nachtrag zu den konzentrationsbezogenen IR-Messungen 322 DANKSAGUNG 324 SELBSTÄNDIGKEITSERKLÄRUNG 327 LEBENSLAUF 328 LISTE AN VERÖFFENTLICHUNGEN 329

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