| The area of polymers confined to different electrode surfaces has received great attention since its inception in 1970's. Polymer-modified electrodes (PMEs), in contrast to metallic or carbon substrate electrodes, can be designed through polymer screening to provide tremendous improvements in sensitivity and selectivity to detect variety of analytes. These electrodes have been demonstrated to be useful for improving ionic permselectivity, the stability and reproducibility of the electrode response, and for favorably realizing electrocatalytic chemical analysis. Also, the electroactive films have been used to entrap different biomolecules at the electrode surface, but without obvious loss of their bioactivity, for the development of biosensors.Electrochemical quartz crystal microbalance (EQCM) is a useful and powerful tool to study polymer-modified electrodes, e.g., the growth process of polymer, ions transport in polymer film. Compared with the conventional electrochemical quartz crystal microbalance that generally records information on the oscillation frequency of a piezoelectric quartz crystal (PQC), the research quartz crystal microbalance (RQCM, with high performance phase lock oscillator circuit) in combination with electrochemistry can be used to synchronously obtain multiple chemical/physical parameters and study materials characteristics during an electrochemical perturbation, such as electrode-mass changes down to the nanogram level, the elasticity of modified films and the solution viscosity and density. The studies in this thesis are summarized as follows:1. The recent progress of the polymer modified electrodes and electrochemical quartz crystal researches is reviewed.2. Piezoelectric diffuse reflectance spectroelectrochemistry (PDRSEC), a new technique of diffuse reflectance spectroelectrochemistry (DRSEC) in combination with electrochemical quartz crystal microbalance(EQCM), has been developed to study the electrochemical copolymerization of aniline and o-anthranilic acid in 1.0 mol L-1 HClO4 and the properties of these copolymers. The DRSEC using an integral sphere was proven to possess a higher optical sensitivity at the unpolished piezoelectric quartz crystal (PQC) electrodes used than the mirror reflectance spectroelectrochemistry mode. The copolymers grown from the copolymerization bath of different molar fraction of o-anthranilic acid (F1, relative to the total amount of the two monomers) showed intermediate properties between those of the homopolymers, which varied gradually with F1. The swelling/dissolution behavior of the copolymers versus solution pH was traced via the EQCM frequency and resistance signals, and its large dependence on F1 was found and discussed. In a HAc-NaAc buffer solution at pH 5.6, the amount of adsorbed lysozyme was found to be positively correlated with F1, via an EQCM impedance investigation, demonstrating the feasibility of using poly(aniline-co-o-anthranilic acid) as a load-adjustable immobilization matrix for cationic proteins.3. Tannic acid-doped polypyrrole (PPY/TA) films have been grown on gold electrodes for selective electrochemical detection of dopamine (DA). Electrochemical quartz crystal microbalance (EQCM) studies revealed that, in vivid contrast to perchlorate-doped polypyrrole films (PPY/ClO4-), the redox switching of PPY/TA films in aqueous solutions involved only cation transport if the solution pH was greater than 3-4. The PPY/TA Au electrodes also exhibited attractive permselectivity for electroactive cations, namely, effectively blocking the electrochemical reactions of anionic ferricyanide and ascorbic acid (AA) while well retaining the electrochemical activities of hexaammineruthenium (III) and dopamine as cationic species. A 500-Hz PPY/TA film could effectively block the redox current of up to 5.0 mmol L-1 AA. The coexistence of ascorbic acid in the measurementsolution notably enhanced the current signal for dopamine oxidation, due probably to the chemical regeneration of dopamine through an ascorbic...
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