Inhibitors used as dopant anions in polymer films are responsible for the anticorrosion behaviour of polypyrrole (Ppy). Ppy film doped with MoO42- and TiF62- showed the role of anions in corrosion protection of iron. Ppy doped with 3-nitro salicylate was used for zinc protection. The results of XPS revealed that molybdate exist in two types: [MoO4]2- (62%) and [Mo7O24]6- (28%). Electrochemical Impedance Spectroscopy (EIS) has indicated the change of the resistance RPM and the capacitance CPM of the Ppy film during reduction. Electrochemical Quartz Crystal Microbalance (EQCM) has shown: the mass of the Ppy film decreased in the cathodic region and increased in the anodic region. The anion flux was also observed in Scanning Kelvinprobe (SKP) and X-ray Photoelectron Spectroscopy (XPS) experiments. The release behaviour of molybdate anions depends much on the size of cations in the electrolyte. TiF62- anions has shown good inhibitor properties. However, the mechanism of this action is not yet known. 3-nitro salicylate (3-nisa) was used as inhibitor dopant for zinc in this work. Ppy film could be formed on Zn without any special pretreatment. The dissolution of Zn decreased dramatically in the presence of 3-nisa. The application of Ppy/metal inorganic composites in corrosion protection for mild steel and galvanised steel may be a better selection. Mixture of core-shell particles with matrix polymer was used as primer for protective coatings.

A urease (Canavalia ensiformis DC.) foi fisicamente imobilizada em matrizes de polipirrol (PPI) com o objetivo de se detectar uréia em amostras padrão. A eletropolimerização do pirrol foi realizada por voltametria cíclica em uma faixa de potencial de -1,0 a 1,0 V vs. ECS em um meio aquoso contendo 0,2 mol/L de \'LI\'CL\'O IND.4\' e 0,1 mol/L de pirrol. Este procedimento permitiu também a imobilização da enzima na matriz polimérica em suas formas, urease purificada (comercial) e como extrato bruto obtido a partir do feijão de porco (Jack Bean), após a adição de 300 \'mü\'g/mL de urease purificada ou 100 \'mü\'L de extrato bruto de feijão de porco. A urease purificada possui 34.375 U/g de sólido e o extrato bruto, 13.000 UA/mL, valores obtidos por titrimetria. A presença da enzima imobilizada nos filmes de PPI foi verificada por voltametria cíclica, FTIR, microscopia eletrônica de varredura (MEV), microscopia de força atômica (AFM) e por uma microbalança de cristal de quartzo (MCQE). A atividade da enzima após a imobilização nos filmes de PPI foi confirmada pela presença de íons amônio em solução, que são formados como produtos da reação de hidrólise da uréia catalisada pela enzima. Como o transdutor influencia a eficiência e a sensibilidade do biossensor, dois métodos de transdução foram estudados: cronoamperometria, aplicando-se um potencial de -0,28 V durante 120 s em tampão fosfato pH 7,0 e a cronopotenciometria, aplicando-se uma corrente de 1,0 mA durante 120 s em tampão fosfato pH 7,0 variando-se a concentração de uréia. O principal objetivo deste trabalho foi avaliar a eficiência do biossensores para a detecção de uréia por meio de transdutores potenciométricos e amperométricos e depois comparar as eficiências dos filmes de PPI/urease purificada e PPI/extrato bruto como biosensores. / Urease (Canavalia ensiformis DC.) was physically immobilized on polypyrrole (PPy) films aiming at detecting urea in standard samples. The electropolymerization of pyrrole was performed by cyclic voltammetry at a potential range from -1.0 to 1.0 V vs SCE in an aqueous medium containing \'LI\'CL\'O IND.4\' 0.2 mol/L and 0.1 mol/L pyrrole. This procedure also allowed us to immobilize the enzyme into the PPy matrix in forms, commercially purified and crude extract of urease obtained from Jack Bean (Canavalia ensiformis) after adding into the electropolymerization media 300 \'mü\'g/mL of purified urease or 100 \'mü\'L of crude extract. The urease solutions had units of active enzyme of 34.375 U/g (purified) and 13.000 UA/mL (crude extract), and the crude extract was obtained from Jack beans by titrimétric methods. The presence of urease immobilized into the PPy film was verified by cyclic voltammetry, FTIR, scanning electron microscopy (SEM), atomic force microscopy (AFM), and by electrochemical quartz crystal microbalance (EQCM) The activity of the enzyme after immobilizing into the PPy films was confirmed by the presence of ammonium ions in solution, since they are formed as catalytic products by urea hydrolysis reaction catalyzed enzyme. The transducer element influences the efficiency and sensitivity of the biosensor, and two transducer methods were studied: chronoamperometry, by applying a potential of -0.28 V during 120 s in buffer phosphate at pH 7.0 and chronopotentiometry, by applying a current of 1.0 mA during 120 s in buffer phosphate at pH 7.0 both after varying the urea concentration. Our main purpose was to evaluate the efficiency of the biosensors for detecting urea by means of potentiometric and amperometric transducers and then compare the efficiencies of PPY/purified urease e PPY/crude extract as biosensors.

The concepts of electroneutrality coupling and electron-hopping, which are useful for the incorporation of functional components and transportation of electrons, were applied in this project. Discrete layered structures were fabricated by sequential electropolymerization to modulate the performances of formate biosensors. Different types of layers, with or without enzyme, were successfully grown on the electrode surface. The presence of the enzyme (formate dehydrogenase), co-factor (B-nicotinamide adenine dinucleotide) and an electron mediator in the polypyrrole film was verified by scanning electron microscopy, chronopotentiometry, cyclic voltammetry and amperometric measurements. Monolayer, bilayer and trilayer formate biosensors were successfully fabricated for different analytical purposes. The utilisation of the biosensing membrane for the reliable batch and FIA determination of formate based on a amperometric mode of detection are explored. Electron mediators such as ferrocyanide, Prussian Blue, ferrocene and ferrocene carboxylic acid were incorporated into the polypyrrole film to lower the required applied potential for amperometric sensing and to maintain the conductivity and stability of the polypyrrole backbone. The application of artificial neural networks (ANN) to overcome the problem of reusability and reproducibilty in a nonlinear and complicated dynamic system is also considered. The resulting system was trained with a new neural network based software package, Turbo Neuron, for prediction of the concentration of formate, based on the entire collected data, which contain the history of the detection experiments. The proposed integrated ANN conducting polymer biosensor enables the determination of formate concentration, both online and in real time / Doctor of Philosophy (PhD)

<p>Cladophora cellulose polypyrrole composites are recognized as potential biomaterials with future applications in hemodialysis. In this project conductive Cladophora cellulose-polypyrrole (clad-ppy) composites were prepared using two different oxidizing agents: iron (III) chloride and phosphomolybdic acid (PMo). Cyclic voltammetry, conductivity and Specific surface area measurements were done to characterize the synthesized composites. Furthermore in vitro blood compatibility studies were performed. Whole blood was incubated with clad-ppy membranes and then blood was analyzed for platelet number reduction and complement activation products (C3a and sC5b-9). Clad-ppy with Iron (III) chloride membranes were found to be superior in terms of conductivity and surface area while Clad-ppy with PMo membranes were found to provoke less blood activation. The results indicated that each oxidizing agent gave distinct properties to the composite material.</p>

Electroactive polymers (EAP) are an emerging branch of smart materials that possess the capability to change shape in the presence of an electric field. Opportunities for the advancement of knowledge were identified in the branch of EAP consisting of inherently electrically conductive polymers. This dissertation explores methods by which the unique properties of composite materials having conductive polymers as a constituent may be exploited. Chapter 3 describes the blending of polyaniline with conventional thermoplastics. Processing these polyblends into foams yielded a porous conductive material. The effect of blend composition and processing parameters on the resulting porous morphology and electrical conductivity was investigated. These findings represent the first systematic study of porous conductive polymer blends. In Chapter 4, multilayer electroactive polymer actuators consisting of polypyrrole films electropolymerized on a passive polymer membrane core were harnessed as actuators. The membrane is vital in the transport of ionic species and largely dictates the stiffness of the layered configuration. The impact of the mechanical properties of the membrane on the actuation response of polypyrrole-based trilayer bending actuators was investigated. Candidate materials with distinct morphologies were identified and their mechanical properties were evaluated. These results indicated that polyvinylidene difluoride membranes were superior to the other candidates. An electrochemical synthesis procedure was proposed, and the design of a novel polymerization vessel was reported. These facilities were utilized to prepare actuators under a variety of synthesis conditions to investigate the impact of conductive polymer morphology on the electromechanical response. Characterization techniques were implemented to quantitatively assess physical and electrochemical properties of the layered composite. Chapter 5 proposes a new unified multiphysics model that captures the electroactive actuation response inherent to conductive polymer trilayer actuators. The main contribution of this investigation was the proposal and development of a new hybrid model that unifies concepts from charge transport and electrochemomechanical models. The output of the proposed model was compared with published data and shown to be accurate to within 10%. Finally, Chapter 6 demonstrated the application of these materials for use as precision mirror positioners in adaptive optical systems.

Cladophora cellulose polypyrrole composites are recognized as potential biomaterials with future applications in hemodialysis. In this project conductive Cladophora cellulose-polypyrrole (clad-ppy) composites were prepared using two different oxidizing agents: iron (III) chloride and phosphomolybdic acid (PMo). Cyclic voltammetry, conductivity and Specific surface area measurements were done to characterize the synthesized composites. Furthermore in vitro blood compatibility studies were performed. Whole blood was incubated with clad-ppy membranes and then blood was analyzed for platelet number reduction and complement activation products (C3a and sC5b-9). Clad-ppy with Iron (III) chloride membranes were found to be superior in terms of conductivity and surface area while Clad-ppy with PMo membranes were found to provoke less blood activation. The results indicated that each oxidizing agent gave distinct properties to the composite material.

The mounting concern for renewable energies from ecologically conscious alternatives is growing in parallel with the demand for portable energy storage devices, fuelling research in the fields of electrochemical energy storage technologies. The supercapacitor, also known as electrochemical capacitor, is an energy storage device possessing a near infinite life-cycle and high power density recognized to store energy in an electrostatic double-layer, or through a pseudocapacitance mechanism as a result of an applied potential. The power density of supercapacitors far exceeds that of batteries with an ability to charge and discharge stored energy within seconds. Supercapacitors compliment this characteristic very well with a cycle life in excess of 106 cycles of deep discharge within a wide operational temperature range, and generally require no further maintenance upon integration. Conscientious of environmental standards, these devices are also recyclable. Electrochemical capacitors are currently a promising candidate to assist in addressing energy storage concerns, particularly in hybridized energy storage systems where batteries and supercapacitors compliment each other’s strengths; however specific challenges must be addressed to realize their potential. In order to further build upon the range of supercapacitors for future market applications, advancements made in nanomaterial research and design are expected to continue the materials development trend with a goal to improve the energy density through the development of a cost-efficient and correspondingly plentiful material. However, it is important to note that the characteristic power performance and exceptional life-cycle should be preserved alongside these efforts to maintain their niche as a power device, and not simply develop an alternative to the average battery. It is with this clear objective that this thesis presents research on an emerging carbon material derived from an abundant precursor, where the investigations focus on its potential to achieve high energy and power density, stability and integration with other electroactive materials. Activated carbons have been the dominant carbon material used in electric double-layer capacitors since their inception in the early 1970s. Despite a wide range of carbon precursors and activation methods available for the generation of high surface area carbons, difficulties remain in controlling the pore size distribution, pore shape and an interconnected pore structure to achieve a high energy density. These factors have restricted the market growth for supercapacitors in terms of the price per unit of energy storage. Activation procedures and subsequent processes for these materials can also be energy intensive (i.e. high temperatures) or environmentally unfriendly, thus the challenge remains in fabricating an inexpensive high surface-area electroactive material with favourable physical properties from a source available in abundance. Double-layer capacitive materials researched to replace active carbons generally require properties that include: high, accessible surface-area; good electrical conductivity; a pore size distribution that includes mesopore and micropore; structural stability; and possibly functional groups that lend to energy storage through pseudocapacitive mechanisms. Templated, fibrous and aerogel carbons offer an alternative to activated carbons; however the drawbacks to these materials can include difficult preparation procedures or deficient physical properties with respect to those listed above. In recent years nanostructured carbon materials possessing favourable properties have also contributed to the field. Graphene nanoplatelet (GNP) and carbon nanotube (CNT) are nanostructured materials that are being progressively explored for suitable development as supercapacitor electrodes. As carbon lattice structured materials either in the form of a 2-dimensional sheet or rolled into a cylinder both of these materials possess unique properties desirable in for electrode development. In the proceeding report, GNPs are investigated as a primary material for the synthesis of electrodes in both a pure and composite form. Three projects are presented herein that emphasize the suitability of GNP as a singular carbon electrode material as well as a structural substrate for additional electroactive materials. Investigation in these projects focuses on the electrochemical activity of the materials for supercapacitor devices, and elucidation of the physical factors which contribute towards the observed capacitance. An initial study of the GNPs investigates their distinct capacitive ability as an electric double-layer material for thin-film applications. The high electrically conductivity and sheet-like structure of GNPs supported the fabrication of flexible and transparent films with a thickness ranging from 25 to 100 nm. The thinnest film fabricated (25 nm) yielded a high specific capacitance from preliminary evaluation with a notable high energy and power density. Furthermore, fast charging capabilities were observed from the GNP thin film electrodes. The second study examines the use of CNT entanglements dispersed between GNP to increase the active surface area and reduce contact resistances with thin-film electrodes. Through the use MWNT/GNP and SWNT/GNP composites it was determined that tube aspect ratio influences the resulting capacitive performance, with the formation of micropores in SWNT/GNP yielding favourable results as a composite EDLC. The third study utilizes electrically conducting polypyrrole (PPy) deposited onto a GNP film through pulse electrodeposition for use as a supercapacitor electrode. Total pulse deposition times were evaluated in terms of their corresponding improvements to the specific capacitance, where an optimal deposition time was discovered. A significant increase to the total specific capacitance was observed through the integration PPy, with the majority charge storage being developed via psuedocapacitive redox mechanisms. A summary of the studies presented here centers on the development of GNP electrodes for application in high power supercapacitor devices. The potential use for GNP in both pure and composite electrode films is explored for electrochemical activity and capacitive capabilities, with corresponding physical characterization techniques performed to examine influential factors which contribute to the final results. The work emphasizes the suitability of GNP material for future investigations into their application as carbon or carbon composite electrodes in supercapacitor devices.

Molecularly imprinted polymers (MIPs) are proving to be very effective in development of synthetic recognition systems and are of great interest to those interested in the field of sensor technology. The use of MIPs is receiving considerable interest due to the ability to prepare recognition matrices that possess high substrate selectivity and specificity. Conducting polymers (CP) have proved to be an excellent tool for the preparation of nano-structured biologically selective systems. Polypyrrole (Ppy) is one such CP that is extensively used for the construction of bioanalytical sensors. Ppy has shown great promise primarily due to its biocompatibility and thermal stability under a variety of environmental conditions. In this study, caffeine imprinted electrodes (CIE) and theobromine imprinted electrodes (TIE) were prepared. This research project subsequently focused on three main aspects: 1) to determine the selectivity of a caffeine and theobromine imprinted MIP using Ppy as the conducting polymer matrix, 2) comparing pulsed amperometric detection (PAD) and electrical impedance spectroscopy (EIS), for their value as potential detection schemes and 3) to determined the applicability of the molecularly imprinted polypyrrole by analyzing commercial samples of instant coffee and tea and comparing results to that obtained from established HPLC procedures. In summary, the following conclusions are stated: - Both PAD and EIS measurements taken from CIE and TIE MIPs showed no statistical difference in response at the 95% confidence level using a standard paired t-test. - Reproducibility for both MIPs was estimated by calculating an average percent relative standard deviation (%RSD) for the corresponding MIPs and was determined to be less than 3%. - The degree of selectivity was estimated by calculating a % relative error for the CIE and TIE electrodes using both PAD and EIS analysis. These results revealed percent relative errors typically less than 5% for equimolar amounts of “interfering” analyte. - A ruggedness revealed that over the concentration range and time interval tested (1-20 mM and 5 days), the average percent relative standard deviation was determined to be less that 7%. - The caffeine content in the coffee sample analyzed, as determined by PAD and EIS, was consistent with results obtained by HPLC analysis however, the theobromine content determined in tea using PAD and EIS was significantly different from that determined by HPLC at the 95% confidence level.

Conducting polypyrrole (PPy) nanoparticles were synthesized via microemulsion polymerization system. The characterization of PPy nanoparticles was done by Fourier transform infrared spectrometer (FTIR) and scanning electron microscope (SEM). Nanocomposites were prepared by melt-mixing of polypyrrole with polypropylene (PP) and processed with injection molding. The amount of PPy in nanocomposites varied in the range of 1-20% by weight. The effect of PPy nanoparticles on mechanical, electrical properties and thermal stability of nanocomposites were investigated. Tensile test has revealed that increasing amount of PPy increased the strength and the stiffness of the nanocomposite while limiting the elongation of PP. Thermal gravimetric analysis has showed that incorporation of PPy nanoparticles has improved the thermal stability of the nanocomposites. Four probe conductivity measurement has exhibited that increasing amount of PPy nanoparticles increases the conductivity of nonconductive PP up to 2,4.10-4 Scm-1. In order to improve the dispersion of PPy in PP, sodium dodecylsulphate was used as dispersant. The same techniques were used to characterize nanocomposites containing 2% by weight dispersant. Composites prepared with dispersant have exhibited improvement in some mechanical and thermal properties and involved smaller dimension PPy nanoparticles.

Conducting polymers have been widely explored for many different purposes including sensing. In thisthesis the conducive properties of pyrrole and the carbohydrate binding properties of boronic acid iscombined to make a reagent-free detector for carbohydrates. The polymer is manufactured in form ofparticles in the μm scale to create a porous film which has a high surface to volume ratio.The material was characterised and the binding properties were evaluated for galactose and glucose.Proof of binding was found via both electrochemical methods and QCM-D. A correlation between R2 value and concentration of substrate was found which enables measurement of concentration of carbohydratesin unknown samples.