This research focuses on the development of a biomimetic photosynthetic energy transduction system which can convert the light energy into a transmembrane potential gradient. This potential gradient provides energy for transmembrane proton pumping, which can be detected potentiometrically and/or spectroscopically through the changes in the optical and electrochemical properties of conductive polymers that supports a lipid bilayer. To achieve this goal, there were two major objectives: 1) Development of a pH sensitive, conducting polymer-based thin film platform as a suitable interface to couple a planar lipid membrane to an ITO electrode and as a pH transducer to detect transmembrane proton motive force (pmf). 2) Construction of an ionophore-aided, transmembrane proton transport model system in a planar supported lipid membrane.Toward the first objective, two different approaches have been used: a) to create a conducting polymer thin film, composed of alternating layers of poly(aniline) PANI and poly(acrylic acid) PAA on an ITO-coated, planar glass substrate. The electroactivity in a neutral environment and the pH dependence of the self-assembled (SA) PANI/PAA multilayer thin films were demonstrated both electrochemically and spectroscopically. Additionally, (PANI/PAA)2 films were shown to be compatible with PSLB. The polymer cushion supported lipid bilayer was found to be highly impermeable to protons, as demonstrated by the blockage of the pH response of the PANI film underneath the lipid membrane. b) to create a PANI nanowire/sol-gel hybrid thin film on an ITO-coated, planar glass substrate. Electrochemical growth of PANI nanowires through a porous sol-gel matrix was demonstrated. The PANI nanowire/sol-gel hybrid thin film with a sol-gel capping layer was found to respond to pH both potentiometrically and spectroscopically and a uniform lipid membrane was formed on the capping layer.To achieve the second objective, a ΔpH-driven transmembrane proton transport model system supported by a PANI nanowire doped sol-gel/ITO substrate with a sol-gel capping layer was developed. Ionophore valinomycin and CCCP were incorporated into the planar supported lipid bilayer (PSLB). Driven by a transmembrane pH gradient, an enhanced rate of proton transport with a proton permeability ca. 3 orders of magnitude higher than that of the lipid membrane without ionophores was demonstrated.

Existing actuators in robotics are noisy, rigid and not very lifelike in their movements. There is a need for actuators in especially limb prosthetics and exoskeletons that are silent, softly moving and preferably operating on low currents. One such solution is the conducting polymers. Textiles are well researched and there is a wide variety of patterning. Even more important is their reproducibility and how easily they are mass-produced. This thesis work combines conducting polymers with textiles to achieve linear textile actuators. The textiles are coated with the conducting polymer Polypyrrole which has the property of volume change, when a voltage is applied and there is a reservoir of ions accessible. The volume change, expansion and contraction, results in a linear actuation. The force and strain are measured while changing different parameters and the results are evaluated in this thesis.

<p>Nanostructures are being intensely studied due to unusual material properties and simple scaling concerns in the microelectronics industry. Fabricating useful nano-scale structures and devices, either by arranging existing nanoparticles such as carbon nanotubes or by manipulating bulk materials into nanometer-scale geometries, is a challenging prospect. One promising approach is to generate a nanometer-scale pattern and transfer that geometry into another material. The research described in this dissertation concerns the fabrication of nanometer-scale patterns, by Atomic Force Microscope-based methods and Electron Beam Lithography, on planar surfaces and the transfer of those patterns into functional materials. Differences in surface energy were used to guide the growth of bulk conducting polymer along predefined nano-scale patterns. Carbon nanotubes were assembled into an ordered and continuous material with no guidance and used to lithographically write silicon oxide nanopatterns on a silicon surface. Finally, the two previous projects were combined, and surface energy patterns were used to guide the deposition of dense carbon nanotube bundles along a planar substrate.</p> / Dissertation

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

The human brain is an extraordinarily complex organ. The process of neurotransmission gives rise to sensory experience, cognition, and decision-making. Many common diseases of the brain are incurable and their symptoms are poorly treated. To better understand the underlying molecular problems in disease states, sensitive, selective, and rapid measurements of biomolecules are needed. Given the complexity of making biological measurements in vitro or in vivo, inquiring scientists must choose measurement tools wisely. While traditional electrode materials have been used to great success, conducting polymers such as PEDOT are an excellent way to modify or improve existing measurement tools. The chemical, spatial, and temporal resolution of in vivo and in vitro measurements can be improved, all while increasing the longevity of the sensor. Compared to existing electrode materials, PEDOT is amenable to a larger variety of substrates, easier to process, inexpensive, and has excellent electrochemical behavior for the detection of neurotransmitters. We have demonstrated the utility of PEDOT by fabricating and characterizing the first device for the separation of biogenic amines, and the first device for high-throughput measurements of exocytosis from single PC12 cells. These devices will allow scientists to inexpensively and rapidly study the effects of pharmacological challenges to model systems in disease states. A PEDOT and Nafion composite polymer coating has been developed for microelectrodes, granting increased sensitivity and selectivity towards dopamine. These improvements resulted in the first in vivo electrochemical measurements of dopamine transients without administration of a reuptake inhibitor. Lastly, we have expanded the chemistry of polythiophenes by developing the synthesis of oligo-EDOT:Nafion nanoparticles. These nanoparticles are easily prepared, inexpensive, and enable quantiative spectroscopic interrogations of water content in organic solvents.

Biological and bio-inspired systems using ion transport across a membrane for energy conversion has inspired recent developments in smart materials. The active mechanism in bioderived materials is ion transport across an impermeable membrane that converts electrochemical gradients into electrical and mechanical work. In addition to bioderived materials, ion transport phenomenon in electroactive polymers such as ionomeric and conducting polymers produces electromechanical coupling in these materials. Inspired by the similarity in transduction mechanism, this thesis focuses on integrating the ion transport processes in a bioderived material and a conducting polymer for developing novel actuation systems. The integrated membrane has a bilayer lipid membrane (BLM) formed on a conducting polymer, and the proteins reconstituted in the BLM regulate ion transport into the conducting polymer. The properties of the polymer layer in the integrated device are regulated through a control signal applied to the bioderived layer and hence the hybrid membrane resembles an ionic transistor. Due to the bioderived nature of this device, it is referred to as a ‘bioderived ionic transistor’. The research carried out in this thesis will demonstrate the fabrication, characterization and design limitations for fabricating a chemoelectromechanical actuator using the BIT membrane. The BIT membrane has been fabricated using BLM (DPhPC) reconstituted with protein (alamethicin) to gate Na$^+$ transport into conducting polymer membrane (PPy(DBS)). In this membrane, the bioderived layer is fabricated with proteins by vesicle fusion method and conducting polymer is fabricated by electropolymerization. The bioderived layers, the conducting polymer layers and the hybrid membrane are characterized using electrochemical measurements such as cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The fabrication, characterization and design effort presented in this thesis focuses on the integration of ion transport through the bioderived membrane into volumetric expansion and bending actuation. The characterization efforts are supported by empirical and physics-based models to represent the input-output relationship for both PPy(DBS) actuator and bioderived membrane, and design rules for the proposed actuation platforms are specified. The electropolymerized PPy(DBS) actuator is anticipated to be used in a bicameral device with the chambers kept separated by the DPhPC-alamethicin bioderived membrane. The relationship between the gradient potential, ionic current through the gate, ion concentration, ion transport coefficient in the conducting polymer layer, and the induced tip displacement in the polymer has been concluded from experiments and fitted to the actuation system model. This thesis will also address future directions for this research and anticipated applications for this hybrid actuation concept, such as artificial muscle, drug delivery.

Neste trabalho, realizamos um estudo da dependência da condutividade elétrica dc ( ), com a dopagem (tempo de exposição ao ácido clorídrico de (0 a 6 horas), temperatura (80 T 300K) e campo elétrico (E) em filmes auto-sustentáveis de polianilina. As amostras foram metalizadas com ouro em ambas as faces e as medidas realizadas utilizando-se o método de duas pontas. O pó utilizado nos filmes foi sintetizado quimicamente através da mistura da anilina com ácido clorídrico, a qual foi adicionada uma segunda solução de peroxidissulfato de amônio e que após desdopagem com hidróxido de amônio, obteve-se a base esmeraldina, esse produto foi dissolvido em N-Metil Pirrolidona possibilitando a obtenção dos filmes pelo método casting e posteriormente dopados por imersão em solução de ácido clorídrico em níveis desejados. Para um curto tempo de exposição ao ácido clorídico (menos de 30 minutos) observamos um rápido crescimento da condutividade com o aumento da dopagem. Para tempos mais longos a condutividade tende a saturação. Da análise da condutividade em função da temperatura obtivemos que ~ exp(T(-1/4)) consistente com o modelo de \"Saltos de Alcance Variável\" proposto por Mott. Nesse modelo a condução ocorre através do tunelamento assistido por fônons entre estados eletrônicos localizados. Se os estados são muito localizados um elétron só poderá saltar para o estado mais próximo, e assim a condutividade será proporcional ao fator de Boltzmann. Se a localização é menos intensa , um elétron pode saltar para sítios onde a energia de ativação é menor mas que estão situados mais distantes do que os primeiros vizinhos, ou seja, a condução ocorrerá por saltos com alcance variável. / In this work, we accomplished a study of the dependence of the dc electrical conductivity ( ), with the doping level (time of immersion of the film into the hydrochloric acid - 0 t 6 hours), temperature (80 T 300K) and electric field (E) in polyaniline thin films. The electric contacts to the samples were obtained using gold deposited in both faces and the measurements have been done using the method of two points. The powder used in the films was synthesized chemically through the mixture of the aniline with hydrochloric acid. A second solution of ammonium peroxidissulfate has been added to the mixture and after that the same has been treated with ammonium hydroxide. The emeraldine base so obtained has been dissolved in N-Methyl-2-pyrrolidinone to be used to produce the films by the method of casting. Later on the films have been doped by imersion with hydrochloric acid in wanted levels. For a short time of immersion into hydrochloric acid (less than 30 minutes) we observed a fast growth of the conductivity with the increase of the doping level. For longer times the conductivity tends to the saturation. Analyzing the conductivity as a function of temperature we obtained that ~ exp (T(-1/4)) consistent with the model of Variable Range Hopping proposed by Mott. In that model the conduction happens through the tunneling of carriers assisted by phonons between localized electronic states. If the localization is very strong, the carrier can only jump to the nearest state, and the conductivity will be proportional to the Boltzmann factor. If the location is less strong, a carrier can jump to sites for which the activation energy is smaller but which can reside further way. As a result we have conductivity with variable range hopping.

SELENOPHENE DERIVATIVES FOR ELECTROCHROMIC APPLICATIONS Aydemir, Kadir M.S., Department of Chemistry Supervisor: Prof. Dr. Levent Toppare February 2008, 60 pages A novel selenophene-based monomer / 1,4-di(selenophen-2-yl) benzene (DSB), synthesized via Stille coupling reaction of 1,4 dibromobenzene and tributyl (2-selenophenyl) stannane and corresponding conducting homopolymer (Poly (DSB)) was electrochemically synthesized in the presence of tetrabutylammoniumhexafluorophosphate (TBAPF6) as the supporting electrolyte in dichloromethane. The resulting conducting polymer was characterized by Cyclic Voltammetry (CV), Fourier Transform Infra Red Spectrometry (FTIR) and Ultraviolet&ndash / Visible Spectrometry (UV-Vis Spectrometry). Spectroelectrochemistry analysis and kinetic studies of Poly (DSB) revealed &ndash / * transition (max) at 340 nm with almost zero percent transmittance (T%) concurrently with striking and rapid (0.6 s) absorbance change at near infrared region (1250 nm) with 35% percent transmittance, indicating that Poly (DSB) is a very suitable near infrared electrochromic material. Copolymer of selenophene with ethylenedioxythiophene (EDOT) was potentiostatically synthesized. Poly (selenophene-co-EDOT) was characterized by Cyclic Voltammetry, FTIR and UV-Vis Spectrometry. During spectroelectrochemistry studies, &ndash / * transition (max) was observed at 555 nm with a switching time of 1.4 s and 39% transmittance. Polaron and bipolaron bands were observed at 851 nm and 1299 nm, respectively. Switching time at 1299 nm was 1.8 s with a percent transmittance of 72. Copolymer of DSB with EDOT (Poly (DSB-co-EDOT)) was synthesized and characterized. max, polaron and bipolaron bands were observed at 457 nm, 696 nm and 1251 nm, respectively. A rapid switching time (0.2 s) with 12% transmittance was observed at 696 nm. At the near infrared region (1251 nm), satisfactory percent transmittance (35%) and a moderate switching time (1.75 s) were observed.

A new polymer with dibenzo[a,e]cyclooctatetraene as the actuation center and one of the thiophene derivatives, 3,4-ethylenedioxythiophene, as polymer chain is successfully synthesized. Nuclear magnetic resonance spectrum is obtained for each synthetic step. Several electrochemistry tests are done to examine the oxidation and reduction properties of the monomer and polymer. Cyclic voltammetry is used for the polymerization. Polymer is first grown on a metallic working electrode and further coated on an ITO plate. UV-Vis experiment is also done. A [pi] [arrow] [pi]* transition is observed as the primary polymer electronic absorption peak. Thickness of the polymer film is also recorded. / text

Neste trabalho, realizamos um estudo da dependência da condutividade elétrica dc ( ), com a dopagem (tempo de exposição ao ácido clorídrico de (0 a 6 horas), temperatura (80 T 300K) e campo elétrico (E) em filmes auto-sustentáveis de polianilina. As amostras foram metalizadas com ouro em ambas as faces e as medidas realizadas utilizando-se o método de duas pontas. O pó utilizado nos filmes foi sintetizado quimicamente através da mistura da anilina com ácido clorídrico, a qual foi adicionada uma segunda solução de peroxidissulfato de amônio e que após desdopagem com hidróxido de amônio, obteve-se a base esmeraldina, esse produto foi dissolvido em N-Metil Pirrolidona possibilitando a obtenção dos filmes pelo método casting e posteriormente dopados por imersão em solução de ácido clorídrico em níveis desejados. Para um curto tempo de exposição ao ácido clorídico (menos de 30 minutos) observamos um rápido crescimento da condutividade com o aumento da dopagem. Para tempos mais longos a condutividade tende a saturação. Da análise da condutividade em função da temperatura obtivemos que ~ exp(T(-1/4)) consistente com o modelo de \"Saltos de Alcance Variável\" proposto por Mott. Nesse modelo a condução ocorre através do tunelamento assistido por fônons entre estados eletrônicos localizados. Se os estados são muito localizados um elétron só poderá saltar para o estado mais próximo, e assim a condutividade será proporcional ao fator de Boltzmann. Se a localização é menos intensa , um elétron pode saltar para sítios onde a energia de ativação é menor mas que estão situados mais distantes do que os primeiros vizinhos, ou seja, a condução ocorrerá por saltos com alcance variável. / In this work, we accomplished a study of the dependence of the dc electrical conductivity ( ), with the doping level (time of immersion of the film into the hydrochloric acid - 0 t 6 hours), temperature (80 T 300K) and electric field (E) in polyaniline thin films. The electric contacts to the samples were obtained using gold deposited in both faces and the measurements have been done using the method of two points. The powder used in the films was synthesized chemically through the mixture of the aniline with hydrochloric acid. A second solution of ammonium peroxidissulfate has been added to the mixture and after that the same has been treated with ammonium hydroxide. The emeraldine base so obtained has been dissolved in N-Methyl-2-pyrrolidinone to be used to produce the films by the method of casting. Later on the films have been doped by imersion with hydrochloric acid in wanted levels. For a short time of immersion into hydrochloric acid (less than 30 minutes) we observed a fast growth of the conductivity with the increase of the doping level. For longer times the conductivity tends to the saturation. Analyzing the conductivity as a function of temperature we obtained that ~ exp (T(-1/4)) consistent with the model of Variable Range Hopping proposed by Mott. In that model the conduction happens through the tunneling of carriers assisted by phonons between localized electronic states. If the localization is very strong, the carrier can only jump to the nearest state, and the conductivity will be proportional to the Boltzmann factor. If the location is less strong, a carrier can jump to sites for which the activation energy is smaller but which can reside further way. As a result we have conductivity with variable range hopping.