An investigation was carried out to discover the effects of high conversion on the kinetic rate coefficients for the polymerisation of styrene. In such regimes, the reaction medium is of such high viscosity that these coefficients (kp and kt) exhibit profound changes. The changes were investigated with respect to the viscosity of and volume fraction of polymer present in the reaction medium. To circumvent the need to polymerise the monomer from the zero conversion, pre-formed polystyrene of known molecular weight was dissolved in purified styrene monomer. The resulting viscous solutions were then polymerised with AIBN as initiator. Effects on kp, kt and a reduction in f, initiator efficiency, were noted. Volume-fraction based models of termination kinetics were shown to be less applicable than one based on viscosity.

A series of five AB block copolymers of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) has been synthesised by the coupling of mono-functional homopolymers by an esterification reaction. In this series polymers all contain a PMMA component of number average molecular weight 908 gmo1·1, as measured by end group analysis, and the PEO components have number average molecular weights of 596, 689, 979, 2023 and 2884 gmol·1, as measured by proton nuclear magnetic resonance spectroscopy. Aqueous "solutions" of these copolymers have been prepared both by direct mixing and via methanol, a solvent for both blocks of the copolymer. Cloud points for these copolymers have been determined and range from 275K to 368K for the lowest and highest PEO blocks respectively. Small angle X-ray scattering (SAXS) of aqueous solutions has been interpreted in terms of a core - shell model and dimensions determined for both. Radii of gyration for the micellar cores have been shown to vary very little with variations in copolymer composition, concentration and temperature up to the cloud point. Fringe thicknesses show a dependence on PEO block length and relating measured fringe thicknesses to calculated chain conformations indicates that the the chain conformation is best described as an unperturbed chain. The measured fringe thickness is not altered by concentration or temperature up to the cloud point. Above the cloud point it is not possible to interpret the SAXS data in terms of a core shell micellar model. Significant differences in the SAXS data have been observed depending upon the mode of addition of copolymer to water. This can be interpreted as differences in micellar II structure With the exception of the lowest molecular weight copolymer all of the copolymers could be used as steric stabilisers for the aqueous emulsion polymerisation of methyl methacrylate. Polymerisations were only successful if the copolymer was introduced to the aqueous phase either via methanol or via the monomer. Direct addition of copolymer to water resulted in low polymerisation rates and unstable/flocculated products. Emulsions produced have been shown to be stable at pH levels where the electrophoretic mobility was zero, ie. the emulsions were sterically stabilised with no contribution from ionic I dipole interactions.

No description available.

No description available.

Since their discovery in the late 1970s conducting polymers have become increasingly used materials in many applications. They are utilised for their conductivity and/or their electroactive properties. These applications include sensor technologies, actuators, and battery materials. The properties of conducting polymers rely on the extent of the reduction / oxidation or redox state, and hence the dopant levels, of the materials. The aim of this work was to investigate the use of the Ion Beam Analysis (IBA) techniques Rutherford Backscattering Spectroscopy (RBS), and Proton Induced X-ray Emission (PIXE) for the analysis of 'soft' organic materials, in particular, conducting polymers. These IBA techniques are not new, as they have been extensively used for the characterisation of many inorganic, 'hard', materials such as aluminium oxide and silicon oxynitride. While they have been used to alter the molecular structure, and hence the properties of conducting polymers in the past, little to no research has explored the use of ion beams as a tool for the characterisation of these materials. Conducting polymers can either be prepared chemically or electrochemically. They are predominantly prepared in an oxidised state and this charge is balanced by negatively charged counter ions. In this work, the conducting polymers were formed electrochemically by deposition onto support materials at constant electrode potential. The number of counter ions required to balance the polymer chain depends on the type of conducting polymer formed and extent of oxidation. Issues such as the influence of the support material and extent of polymer oxidation on the extent of counter ions through the polymer films are of importance. Gaining knowledge of the dispersion of counter ions may provide new insights into the redox mechanisms for conductive polymers. Complex bis terthiophene porphyrin conducting polymers were prepared and investigated for the uptake of zinc into the freebase porphyrin unit after polymerisation by acquiring elemental depth profiles using RBS analysis. Issues such as the influence of the support material and extent of polymer oxidation on the extent of counter ions through the polymer films were found to be of importance. Gaining knowledge of the extent of counter ions provides new insights into the redox mechanisms for conductive polymers. The results were compared to those obtained for a sample where zinc was coordinated to the porphyrin prior to the polymerisation process. Unexpected high concentrations of both nitrogen and oxygen were found, which were interpreted to be due to entrapped cations originating from the electrolyte ((Bu)4N+), together with trapped water molecules, within the polymer films. The chlorine depth profiling assisted with understanding the extent of the perchlorate counter ion throughout the polymer films. The combination of both RBS and PIXE demonstrated that trace element impurities can be detected using ion beam analysis, which other analytical techniques are unable to do. A series of polypyrrole films incorporating a range of counter ions were prepared as model compounds for study in the second section of this work. RBS and PIXE techniques were used to evaluate film homogeneity with respect to depth and to infer the counter ion / pyrrole unit ratio for each of the six PPy film formed. RBS was also used to characterise a series of terthiophene-ferrocene based conducting co-polymers. The ratio of co-polymer monomer to terthiophene-ferrocene monomers and the dopant levels for the polymers were determined using a RBS deconvolution method developed in this study. This new method can be extended for characterization of a wide range of organic polymers. The limitations of RBS for the analysis of these soft materials were identified. The advantage that RBS offers over other analytical techniques is that it provides a means for low atomic number element depth profiling in these materials.

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No description available.

Geopolymerisation can transfer A1 and Si containing wastes into geopolymers with a high mechanical strength and high fire, acid and bacteria resistances. This thesis investigates the geopolymerisation of natural aluminosilicate minerals which cover a wide range of structures, minerals groups, hardness, densities and A12O3 and SiO2 contents. The study of fifteen selected A1-Si minerals shows that the framework structured A1-Si minerals with a high CaO content and a lower K2O content, have a higher potential to undergo geopolymerisation in KOH solution with resulting geopolymers possessing a higher compressive strength. The NaOH solution is observed to leach more A1 and Si complexes from the solid reactants than KOH solution, while KOH solution produces geopolymers with a higher mechanical strength than NaOH solution does. (For complete abstract open document)

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No description available.