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Conductivity and electron spin resonance measurements have been performed on solution doped polyaniline (PANi). It is proposed that both camphor-sulphonic acid (CSA) and 2-acrylamido-2-methyl-l-propanesulphonic acid (AMPSA) doped PANi can be described by the same model. It is suggested that the polyaniline materials are composed of differently ordered layers, a highly ordered region forming the core of the crystallites. The core of the crystallites are believed to be encapsulated within a semi- ordered region, with the crystallites themselves being dispersed in an amorphous polymer matrix. The conductivity measurements and ESR results described in this work support the proposal that within the highly ordered region of doped polyaniline crystallites, a polaronic lattice exists. The polaronic lattice facilitates "free" carriers which are responsible for "metallic" conduction within the crystallites. Encapsulating the polaronic lattice is a semi-ordered region in which (partially) mobile polarons (and possibly bipolarons) are present. The highly conductive crystallites are randomly dispersed in a less conductive polymer matrix. Charge transport within this heterogeneous system is well described by a heterogeneous metal - fluctuation induced tunnelling (FIT) model. The differences in the temperature dependent conductivities of the PANi-CSA and PANi-AMPSA materials are attributed to the systems having layers of different relative sizes (in the above model). AMPSA doped polyaniline films had a maximum room temperature conductivity of ~100 Scm(^-1). This material also showed potential for use as an electrode layer in polymer LEDs, to replace ITO coated glass. The conductivity of PANi-AMPSA was measured to be 50 ± 10 Scm(^-1) at thickness' of ~30nm. Layers of this thickness provide >90% optical transmission between 450 and 675 nm (most of the visible spectrum). Faraday rotation measurements have shown that the recently reported large Faraday rotation of polyaniline can not be reproduced. The limited results of the Faraday rotation experiments described in this work provide support for the theory that charge carriers in polyaniline have an effective mass of at least 100 times that of a free electron. It has also been shown that the claims of a polyaniline derivative (namely the Marcoussis polymer) being an entirely organic ferromagnet are unsubstantiated, despite intense investigation.

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This research focuses on the development of spectroelectrochemical sensor formats based on thin film molecular architectures and electrochemical detection of sol-gel encapsulated macromolecular recognition elements. To achieve this goal, there were two major objectives: 1) to demonstrate and characterize conductive polymer grown electrochemically in porous sol-gel thin films with specific regard to the ability of the polymer to mediate charge transfer between sol-gel encapsulated molecules and the electrode surface, and 2) to develop a means to probe the spectroscopic properties of highly absorbent thin films as a function of applied potential. Toward the first objective, diffusion of a derivatized thiophene monomer into a sol-gel thin film and subsequent electropolymerization at an underlying indium-tin oxide (ITO) surface was found to produce a conductive network of polymer capable of mediating electron transfer from encapsulated redox centers in the bulk of the sol-gel film to the electrode surface. At high levels of polymer loading, emergent, sol-gel templated, polymeric structures are formed which extend from the sol-gel surface into the electrolyte solution and exhibit electrochemical properties of ultramicroelectrode arrays. To achieve the second objective, a polychromatic, electroactive attenuated total internal reflectance (EA-ATR) instrument was developed consisting of an indium-tin oxide (ITO) coated glass internal reflection element (IRE). In addition to a high degree of surface sensitivity relative to transmission geometries, this geometry affords acquisition of absorption anisotropy information, via polarization of the incident beam, to determine the orientation distribution in molecular adlayers. To demonstrate these abilities, the orientational distribution of monolayer and bilayer films of perylene and copper phthalocyanine derivatives, respectively, was determined. Furthermore, it was demonstrated that the EA-ATR could be used in a potential-modulated mode (PM-ATR) to study the kinetics of electro-optical switching in conductive copolymer thin films.

The positive temperature coefficient (PTC) effect in conductive polymer composites (CPC) are still poorly understood with the thermal expansion of the polymer matrix accepted as the main cause. This thesis aims to study a model system able to explain the effect of the filler size and shape on the PTC behaviour of CPCs. Silver coated glass spheres and flakes are used as conductive fillers due to the ease in controlling uniform size and shape. In a controlled system it was demonstrated that the PTC intensity increases with increasing filler size and with decreasing filler content, both for conductive fillers. Combinations of different conductive fillers were investigated to explore the possibility to obtain both low percolation thresholds and high PTC intensities. Model systems in which at least one of the two conductive fillers is of relatively homogenous size and shape were used to facilitate unravelling some of the complicated relationships between (mixed) conductive fillers and the PTC effect. The PTC intensity of mixed fillers composites were dominated by the filler with the lowest PTC intensity, even at very low volume fractions. The PTC intensity was not only influenced by the conductive particle size but also by its size distribution. The effect of difference in linear coefficient of thermal expansion (CTE) of conductive fillers and polymer matrix based on a change in filler core on PTC behaviour was investigated. Damage to the particles due to the poor adhesion between the silver coating and the PMMA bead lead to the composite behaving like mixed filler composite. Hybrid polymers filled with silver coated glass flakes was also examined in order to enhance the PTC intensity. The PTC intensity of the composite increased with increasing PPE content but the negative temperature coefficient (NTC) effect was observed in all the composites.

We present a novel thylakoid based bio-solar cell capable of generating a photoelectric current of    0.7 µA/cm2. We have introduced an electro conductive polymer, PEDOT-S, to the thylakoid membrane. PEDOT-S intervenes in the photosynthesis, captures electrons from the electron transport chain and transfers them directly across the thylakoid membrane, thus generating a current. The incorporation of the electro conductive polymer into the thylakoid membrane is therefore vital for the function of the bio-solar cell. A liposomal model system based on liposomes formed by oleic acid was used to develop and study the incorporation of PEDOT-S to fatty acid membranes. The liposomes allow for a more controllable and easily manipulated system compared to the thylakoid membrane. In the model system, PEDOT-S could successfully be incorporated to the membrane, and the developed methods were applied to the real system of thylakoid membranes. We found that a bio-compatible electrolyte and redox couple was required for this system to function. The final thylakoid based bio-solar cell was evaluated according to performance and reproducibility. We found that this bio-solar system can generate a low but reproducible current.

In this study, a conductive polymer is used as tool electrode in machining the stainless steel surface by electrochemical buffing. Using a very small working current of this conductive polymer, the material of the workpiece is dissolved, and the peaks on the workpiece surface is buffed by the abrasive simultaneously. A mirror-like surface can be achieved with high efficiency using this novel method. In the micro-electrochemical machining experiments, the initial surface roughness of the workpiece is about Rmax = 1.645 £gm, the average speed of electrode 25 mm/sec, the machining time 10 min, the electrolyte temperature 25¢J, and the stroke 10 mm. The variable conditions are given as follows: the sodium nitrate (NaNO3) electrolyte of 0 to 40 wt%, the normal load of 0 to 20 N, and the working current of 0 to 100 mA. Experimental results show that the minimum surface roughness of the workpiece can be achieved to about Rmax = 0.3£gm at the electrolyte concentration of 20 wt%, the working current of 25 mA, and the normal load of 10N, which is selected as the optimum operative parameters in the following. The silicon carbide with average particle size of 9.5£gm is added to conduct the electrochemical buffing experiments. Compared with the micro-electrochemical machining method, results show that the maximum machining depth increases to about two times, and the surface roughness decreases to about 50%. In this condition, the mirror-like surface of the workpiece with the working depth of 1.5£gm and Rmax of 0.15£gm can be achieved.

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Conductive polymers are promising pseudo capacitive materials as they feature both good conductivity and high capacitance. Formation of composite between conductive polymers and carbon nanotubes is a proven technique in enhancing the material electroactivity. In-situ polymerization of conductive polymers includes polyaniline, polypyrrole and PEDOT: PSS and composite with MWCNT has been successfully achieved. Composites fabricated by using different dopants and their performance were studied. Excellent achieved capacitive performance is due to the combination of pseudo capacitance and double layer capacitance. The MWCNTs content has significant influence on the morphology and structure of the polymerized ECP in the composite. And therefore affects the material conductivity and the charge storage performance. Two electrodes cell performance shows that Ppy/MWCNT composite shows a more promising performance as electrode materials for EC applications in contrast to PANI/MWCNT and PEDOT: PSS/MWCNT composites.

Conductive polymers are promising pseudo capacitive materials as they feature both good conductivity and high capacitance. Formation of composite between conductive polymers and carbon nanotubes is a proven technique in enhancing the material electroactivity. In-situ polymerization of conductive polymers includes polyaniline, polypyrrole and PEDOT: PSS and composite with MWCNT has been successfully achieved. Composites fabricated by using different dopants and their performance were studied. Excellent achieved capacitive performance is due to the combination of pseudo capacitance and double layer capacitance. The MWCNTs content has significant influence on the morphology and structure of the polymerized ECP in the composite. And therefore affects the material conductivity and the charge storage performance. Two electrodes cell performance shows that Ppy/MWCNT composite shows a more promising performance as electrode materials for EC applications in contrast to PANI/MWCNT and PEDOT: PSS/MWCNT composites.