Der Mechanismus der Miniemulsionsbildung bzw. polymerisation wird eingehend untersucht. Dabei werden Faktoren, wie die Tensidmenge, Ultraschalldauer und die Teilchengröße untersucht. Besonders werden auch noch Aspekte wie Stabilität der Emulsion und Kinetik während der Polymerisation untersucht. / The mechanism of the formation and polymerisation of the miniemulsion respectively is thoroughly investigated. Parameters such as surfactant amount, duration of ultra sound and particle size are surveyed. Special emphasize is given to the aspects of stability of the emulsion and the kinetic of the polymerisation. <br><br> ---- <br><br>Anmerkung:<br> Die Autorin wurde 2001 mit dem Publikationspreis des Leibniz-Kollegs Potsdam für Nachwuchswissenschaftler/innen in den Naturwissenschaften ausgezeichnet.

Results of an inter-laboratory round-robin study of the application of time-resolved emission spectroscopy (TRES) to the speciation of uranium(VI) in aqueous media are presented. The round-robin study involved 13 independent laboratories, using various instrumentation and data analysis methods. Samples were prepared based on appropriate speciation diagrams and, in general, were found to be chemically stable for at least six months. Four different types of aqueous uranyl solutions were studied: (1) acidic medium where UO22+aq is the single emitting species, (2) uranyl in the presence of fluoride ions, (3) uranyl in the presence of sulfate ions, and (4) uranyl in aqueous solutions at different pH, promoting the formation of hydrolyzed species. Results between the laboratories are compared in terms of the number of decay components, luminescence lifetimes, and spectral band positions. The successes and limitations of TRES in uranyl analysis and speciation in aqueous solutions are discussed.

Calamitic (rod-shaped) and discotic (disc-shaped) thermotropic liquid crystalline (LC) compounds were spread at the air-water interface, and their ability to form monolayers was studied. The calamitic LCs investigated were found to form monolayers which behave analogously to conventional amphiphiles such as fatty acids. The spreading of the discotic LCs produced monolayers as well, but with a behaviour different from classical amphiphiles. The areas occupied per molecule are too small to allow the contact of all hydrophilic groups with the water surface and the packing of all hydrophobic chains. Various molecular arrangements of the discotics at the water surface to fit the spreading data are discussed.

The aqueous solubilization power of several series of micellar homopolymers and copolymers (polysoaps) is investigated. Using five insoluble or poorly water-soluble dyes, comparisons of the capacities are made with respect ot the influence of structural variables such as the polymer backbone, the polymer geometry, the comonomer content, and the charge of the hydrophilic group. Some guidelines for polysoap structures suited for efficient solubilization are established. Noteworthy is that the solubilization capacities of the polysoaps are neither linked to the ability to reduce the surface tension of water, nor to the polarity of the solubilization sites deduced from spectroscopic probes.

This work has used laser light scattering to investigate the possible existence of inhonogeneities and other defects in an epoxy resin system, and the role these defects play in the mechanical and electrical failure of the polymer. Mie Theory was used in the analysis of the data throughout this thesis. Ultra clean fully degassed samples were prepared to ensure any scatterers observed were Inherent to the sample. It was discovered that inhomogeneities and microvoids do exist in the fully cured and degassed ultra clean samples before stressing. Reproducible trends in inhomogeneity behaviour were observed on stressing, and a three phase model of inhomogeneity has been proposed to explain this behaviour. This consists of a densely crossllnked core of mainly diester crosslinks, surrounded by a less densely crosslinked network containing more ether crosslinks. These regions are then interconnected by a weaker even less densely crossllnked matrix where it is proposed that initial yield occurs followed by eventual failure. Voids present in the network were observed to grow in a similar manner under both mechanical and electrical stress. This suggests a possible link in the deformation processes under either stress. On release of both types of stress, relaxation occurred and the voids reduced in size although some hysteresis was observed. One distribution of voids reached a plateau in size with applied electrical and mechanical stress and this suggests that not all defects have the potential to cause failure. No wholly reproducible trends were observed for the samples that underwent electrical stress. A common observation was a step type of behaviour that occurred on the release of stress, and also during stressing around a field value of 2.0 x 10[to the power of]6 kV m[to the power of]-1. The later has been attributed to failure occurring at the pin tip epoxy interface causing relaxation in the scattering volume. The overall behaviour with applied stressed varied from sample to sample and has been attributed to complicated mechanical and electrical forces present and the remoteness of the scattering volume from the pin tip. The scattering volume, however is very much affected by what is occurring at the pin tip. It is concluded that the defects present in the epoxy resin do play an important role in the deformation and failure of the polymer. The defomation process under both electrical and mechanical stress are thought to be the same and the deformation under electrical stress results from the mechanical force associated with the electric field.

Nuclear Magnetic Resonance (nmr) spectroscopy has been employed to determine molecular geometries, anisotropies in the indirect spin-spin couplings and chemical shifts, quadrupolar coupling constant, signs of indirect spin-spin coupling constants and conformational preferences of selected molecules by using isotropic and oriented solvents.

The work presented in this thesis has involved an investigation of the thermal decomposition of the Michaelis-Arbuzov intermediates (PhO)3PMeBr, (PhO)3PMeI, (o-CH3C6H40)3PMeBr, and (o-CH3C6H40)3PMeI, in the solid state and in deuterochloroform.

Reactions of highly hindered phosphorus (III) esters derived from 2,2,2-triphenylethanol, 2,2-diethylbutan-1-o1, and norbornan -1-o1 with electrophilic reagents, in particular, α-haloketones were studied by P and pH spectroscopy.

The synthesis of the complexes Cr(1-nqo)3, Cr(2-nqo)3, Cr(3-Me-5-OHqo)3, Cr(6-Me-5-OHqo)3, Mn(1-nqo)3, Mn(2-nqo)3, Mn(1-nqo)2, and Mn(2-nqo)2, has been systematically examined.

The electrochemical reduction of a series of quaternary phenacyclammonium and tertiary phenacylsulphonium salts in aqueous solution at a mercury cathode has been investigated using polarography, coulometry, titrimetry and product analysis methods.