Thesis (M.A.)--York University, 2007. Graduate Programme in Music. / Typescript. Includes bibliographical references (leaves 100-103). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR38793

Thesis (Ph. D.)--University of Texas at Austin, 2001. / Vita. Includes bibliographical references. Available also from UMI Company.

Conducting polymers have been extensively investigated in a wide range of applications due to their ability to achieve near metallic conductivity while possessing the flexibility and processability of traditional polymers. However, interchain and solid-state effects have made direct investigation of the polymer systems difficult. A series of systematically varied model compounds have been designed to provide detailed information about through-chain charge transport in well-defined oligothiophenes. Our design incorporates two metal binding pockets at either end of an oligothiophene bridge to investigate the interaction of redox centers and charge transport properties between conducting polymers and bound transition metal centers. Synthesis, characterization, electrochemistry, and detailed EPR investigations of this new series of oligothiophene model compounds and the analogous mononuclear compounds will be discussed herein. Conjugated polymer matrices possess a large number of available oxidation states making them an attractive choice for use as redox-active ligands. This variety of oxidation states offers a means to easily tune the amount of electron density on a metal center and consequently affect the binding of an additional ligand. Our approach utilizes conducting metallopolymers with metal complexes synthetically incorporated directly into the conducting polymer backbone. The redox-dependent properties of this class of materials and their development as small molecule storage and delivery systems have been explored utilizing a variety of novel electropolymerizable transition metal complexes. The design, synthesis, characterization, and redox-affected properties of the monomers, corresponding conducting metallopolymers, and model complexes are discussed. The tub-shaped dibenzo[a,e]cyclooctatetraene molecule undergoes a large change in geometry upon reduction to form the planar aromatic species. Herein, we seek to prepare and investigate a supramolecular assembly utilizing this redox-active molecule. In contrast to electrochemically active frameworks where redox changes occur at the metal centers, incorporation of a functionalized dibenzo[a,e]cyclooctatetraene ligand into an assembly has the potential to result in a redox-active framework. Not only would the redox-activity occur at the organic bridge, but reduction of the system should result in a large geometry change. / text

This dissertation focuses on the development of biomaterials that could be used to enhance the regeneration of severed peripheral nerves. These materials were designed to be electroactive, biodegradable, and biocompatible. To render the materials electroactive the author chose to incorporate conducting polymer (CP) units into the materials. Because CPs are inherently non-degradable, the key challenge was to create a CP-based material that was also biodegradable. Two strategies were explored to generate a biodegradable CP-based material. The first strategy centered around the incorporation of both electroactive and biodegradable subunits into a copolymer system. In the context of this approach, two bis(methoxyquaterthiophene)-co-adipic acid polyester (QAPE) analogues were successfully synthesized, one through polycondensation (giving undoped QAPE) and the second through oxidative polymerization (giving doped QAPE-2). QAPE was found to be electroactive by cyclic voltammetry, bioerodible, and cytocompatible with Schwann cells. QAPE was doped with ferric perchlorate, although only a low doping percentage was realized (~8%). Oxidative polymerization of a bis(bithiophene) adipate permitted the direct synthesis of doped QAPE-2, which was found to have a higher doping level (~24%). The second strategy pursued with the goal of generating an electroactive biodegradable material involved covalently immobilizing low molecular weight polythiophene chains onto the surface of crosslinked hyaluronic acid (HA) films. HA films are not only biodegradable and biocompatible, but they also provide mechanical integrity to bilayer systems. Dicyclocarbodiimide coupling of carboxylic acids to HA alcohol groups was used to functionalize HA films. The HA-polythiophene composite is still in the early stages of development. However, to date, thiophene has been successfully immobilized at the surface of HA films with a high degree of substitution. The author has also shown that thiophene polymerization can be achieved at the surface of these functionalized films and that the extent of polymer immobilization appears to be affected by the presence of immobilized thiophene. The results reported in this dissertation lead the author to suggest that it is possible to generate biodegradable electroactive materials. Further, she believes that with additional optimization these materials may prove beneficial for the regeneration of peripheral nerves and possibly other tissues that respond favorably to electrical stimulation. / text

Conducting metallopolymers are a new and fascinating class of materials that incorporate metals into conducting polymer systems. These new materials combine the processing advantages of polymers with the electronic, optical and catalytic properties provided by the presence of metal centers. A large number of conducting metallopolymers have been synthesized and studied and have found applications in areas such as sensors, memory and light-emitting devices, solar cells, and catalysis. Among the various applications, conducting metallopolymers as emitting layers in high-efficiency polymer light-emitting diodes (PLEDs) attract great research interest. In order to get PLEDs with long lifetime, high quantum efficiency, and excellent color purity, we have developed an approach to synthesize well-defined conducting metallopolymers that incorporate lanthanide complexes in an inner sphere fashion. As such, we aim to take full advantage of the properties of both organic and inorganic components with high efficiency due to the direct electronic interface this configuration creates. Lanthanide complexes with polymerizable groups have been synthesized, characterized and utilized as precursors for conducting metallopolymers. These lanthanide monomers and corresponding metallopolymers display visible and near-infrared luminescence at room temperature that is consistent with efficient energy transfer from the organic polymer matrix to the lanthanide metal ion followed by lanthanide luminescence. As a second but closely related area, electrogenerated chemiluminescence (ECL) of polymers is attractive for light-emitting devices. Up to now, there are limited studies dealing with ECL from pure active materials deposited as solid films on electrodes. The operation theory and degradation mechanism are still under investigation. To advance the development of ECL of conducting metallopolymers, we prepared cyclometalated Pt(II) complexes with polythiophene system. Conducting metallopolymer films are prepared through controlled electropolymerization. ECL of the Pt(II) containing conducting polymers are observed for the first time. Finally, a preliminary study of magnetism and conductivity of conducting metallopolymers has been done. We incorporate Fe(II)/Fe(III) into our newly designed ligand systems with polymerizable thiophene derivatives. Three complexes show spin crossover (SCO) phenomena with the highest transition temperature at 265 K, which are further verified by variable temperature electron paramagnetic resonance spectra. / text

In this thesis, fabrication of polymer solar cells through different device designs is presented and the resulted solar cell performance is discussed. Poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are chosen as the photoactive layer materials as this material combination has been widely used and well investigated. The known properties of P3HT and PCBM make systematical studies and modeling for the effect of device designs on the performance of polymer solar cells possible although this is beyond the scope of this thesis. First, ITO electrodes were fabricated by sputtering and used as the transparent electrode for polymer solar cells. Properties of ITO film fabricated by different sputtering conditions were compared. Radio frequency (RF) sputtered ITO was found to exhibit the best transparency overall. This condition was further applied to the fabrication of ITO electrode for polymer solar cells with light trapping structures. Low temperature processed silicon oxide (SiOx) / titanium oxide (TiOx) periodic structures were fabricated by sol-gel method. Optical transmittance of the bottom electrode was altered by the presence of the reflective coating and thus the absorption in the photoactive layer was affected. By varying the number of layer pairs and thickness of each layer in the reflective coating, improvement of polymer solar cell performance was found by inserting reflective coating for optimized conditions. Finally, semi-transparent polymer solar cells with inverted structure were demonstrated using conductive polymer as the anode. The process in device preparation was vacuum-free and thus could be potentially useful in large-scale roll-to-roll fabrication. / published_or_final_version / Physics / Master / Master of Philosophy

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Lecture: Igor Stravinsky's stylistic shift: A comparative analysis of the 1911 and 1947 versions of Petrushka -- Petrushka (1947) / Igor Stravinsky / text

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