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Conducting polymers display properties such as high conductivity, light weight and redox activity giving them great potential for use in many applications. Polythiophenes have proved to be particularly useful because they are readily functionalised and have good chemical stability. The purpose of this work was to investigate the effect of electron-withdrawing and electron-donating substituents on the synthesis and properties of polythiophenes. Initial work entailed the synthesis of a series of styryl-substituted terthiophenes. Polymerisation of these materials using both chemical and electrochemical methods was found to produce predominantly short chain oligomers (n < 4) and insoluble material that could not be further processed. An analogous series of styryl-substituted terthienylenevinylene materials were electrochemically oxidised for comparison to the terthiophene series. These materials were also found to produce predominantly dimer and short oligomers, but with the expected higher conjugation length than the corresponding terthiophene oligomers. To enhance polymerisation and increase the solubility of the resulting materials, the polymerisation of styryl-terthiophenes with alkyl and alkoxy functionalities was investigated. The properties of the resulting polymeric materials were determined using electrochemistry, mass spectrometry, spectroscopy and microscopy. The alkoxy substituted polymer was found to have a longer average polymer length than the corresponding alkyl derivative (~n = 11 compared to ~n = 6), but was less soluble (78% compared to 100%). It was found, however, that by increasing the alkoxy chain length from 6 carbons to 10 carbons, the solubility of the polymer could be increased to 97% without affecting the average polymer length. The alkoxy-substituted polymers were observed to be very stable in the oxidised, conducting state compared to the alkyl-substituted polymer, which appeared to be more stable in the neutral, non-conducting state. It was found that these soluble materials could be separated into fractions of different length polymers by using sequential soxhlet extractions in different solvents. Preliminary investigations were made into the suitability of these soluble oligomeric and polymeric materials for use in photovoltaic, actuator and organic battery applications and promising results were achieved for actuator and battery functions. In addition, the solubility of these materials allowed nano- and micro-structured fibre and fibril surfaces to be prepared for use in high surface area electrodes.

The thesis introduces a new quantitative safety modelling approach for large scale socio-technical systems that exhibit Low Probability High Consequence (LPHC) accidents. This approach uses Bayesian Belief Networks (BBN) and overcomes inherent difficulties of current methods, difficulties that make these methods incapable of coping with complexities of socio-technical systems.

The research described in this thesis investigated a range of techniques for the in situ polymerisation of thiophene-based intrinsically conductive polymers (ICPs) on textile substrates. Following a review of the literature, three potentially useful techniques were identified; a simple aqueous technique; a vapour phase technique; and a two-stage impregnation technique. The literature also indicated that thiophene-based ICPs were likely to be more durable than those prepared from other precursors. The aqueous technique proved unsuccessful, but both the vapour and two-stage impregnation techniques were used to prepare textile-ICP composites using 2,2'-bithiophene and 3,4-ethylenedioxythiophene (EDOT). Polymerisation was effected by chemical oxidation of the precursor, with iron (III) salts being the best oxidants. The main drawbacks of the vapour system were the long vapour exposure times (e.g. several days) and/or elevated temperatures required to polymerise these relatively unreactive precursors. Two-stage impregnation was somewhat messy and inefficient, so a novel refinement of the technique (referred to as 'single dip') was developed. With this system, the specimen was impregnated with both precursor and oxidant from a single solution, then removed from the solution and the solvent allowed to evaporate. It was only at this stage that polymerisation occurred, and when more reactive ICP precursors (such as pyrrole) were used, polymerisation tended to occur in solution, and was less effective. The influence of various treatment parameters was established, while tests confirmed that the deposited ICP layer had no detrimental effect on the desirable fabric properties of flexibility and strength. Composites with surface resistance as low as 65 Ω/square were prepared with less than 6% ICP load on the textile (perchlorate-doped poly(EDOT)). The durability of poly(EDOT) composites was far better than polypyrrole under ageing in ambient conditions, accelerated ageing at elevated temperatures, and when given a treatment that simulated laundering. Finally, a scheme for continuously depositing ICPs onto textiles by this approach was designed, as a way of demonstrating the potential for scale-up of the system.

A recently proposed route to magnetized target fusion (MTF) has been developed [4] which utilizes an array of high velocity pulsed plasma accelerators, fired in unison at a target plasma. The plasma accelerators are required to be capable of reproducible results of 0.2mg of hydrogen plasma at velocities in excess of 200km/s and be possible of operating at 10Hz. No previously developed pulse plasma accelerator is capable of these results. The purpose of this thesis was to develop a plasma accelerator for application to the proposed fusion scheme. The previously unexplored possibility of using a piezoelectric valve in these devices was investigated. The piezoelectric valve that was developed is capable of generating reproducible, short, well defined hydrogen pulses with longitudinal temperatures below 2K. Presently the valve can deliver a maximum output of 0.022mg of hydrogen gas. A unique coaxial plasma accelerator, the Lica was developed that has three main features that set it apart: 1) it uses a piezoelectric valve to deliver short well defined hydrogen pulses into the accelerator, 2) the gas is linearly injected into the device and 3) it uses a novel preionization method. Currently the Lica is unable to offer the performance required for the proposed fusion scheme, the bulk of the plasma generated in this device appears to be travelling the region of 40-50km/s at a temperature of 3000K to 5000K. There are a few anomalies in the operation of this device: 1) it appears to accelerate a series of plasma sheaths in the regions of 40km/s, 50km/s and 60-80km/s, 2) the final plasma velocity appears to be independent of the acceleration distance and in some instances high velocity plasma in the region of 200km/s was observed. A numerical finite element model (FEM) electromagnetic model called MATAC was developed to try and simulate the operation of the Lica, because it was shown that simple analytical models are inadequate. The preliminary modelling efforts predicted the final velocity of the bulk of the plasma to be 82.6km/s. A spin off from the development of the numerical model was the extension of the upwinding scheme of [157] to quadratic and cubic FEM elements.

The static dipole polarizabilities and ionization potentials of the first and second main group elements, including the charged ions, are obtained from all-electron relativistic coupled-cluster theory using a scalar relativistic Douglas-Kroll Hamiltonian. Spin-orbit coupling effects are investigated using a fully relativistic four-component Dirac-Coulomb-Hartree-Fock scheme followed by a second-order many-body perturbation treatment to account for electron correlation. Periodic trends in the dipole polarizabilities and the ionization potentials are discussed. In each case, a detailed discussion on electron correlation and relativistic effects are given. A relationship for relativistic and electron correlation effects between the dipole polarizability and the ionization potential is established. Particular attention is paid to the evaluation of a near basis set limit quality of the dipole polarizabilities. This is accomplished by the evaluation of all-electron basis sets used, followed by an extensive study on the convergence behavior of the dipole polarizabilities with respect to a finite basis set expansion. The present all-electron dipole polarizabilities are believed to be very precise, especially for charged ions where the availability of experimental values are limited. Scalar relativistic small-core pseudopotentials are fitted and their performance is tested in terms of static dipole polarizabilities and ionization potentials. It is demonstrated that the small core definition of the pseudopotential (nine-valence electron for the main group 1 and ten-valence electron for the main group 2 elements) enables us to safely omit core-valence correlation without scarifying accuracy. Following atomic dipole polarizabilities, applications are made to molecules starting with alkali dimers and their singly charged ions. The scalar relativistic pseudopotentials of this study are used to calculate equilibrium bond lengths, dissociation energies, vibrational frequencies and the dipole polarizabilities of these dimers. The change in the molecular dipole polarizabilities from the corresponding atomic dipole polarizabilities are discussed in terms of molecular bonding models. Simple ammonia complexes of the alkali-metals and their singly charged ions are studied. The equilibrium geometries, dissociation energies, harmonic vibrational frequencies as well as the dipole polarizabilities of these complexes are given.