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 Title: Characterization of polymer-modified electrodes from transient ultramicroelectrode experiments Author(s): Barton-Taylor, Marvin Eric Doctoral Committee Chair(s): Faulkner, Larry R. Department / Program: Chemistry, Analytical Discipline: Chemistry, Analytical Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Chemistry, Analytical Abstract: Reliable diffusion coefficients and concentrations have been obtained simultaneously by fitting chronoamperometric transients of an ultramicroelectrode to the split function derived by Aoki and Osteryoung. An extensive investigation into the effect of noisy data and small bias currents on the diffusion coefficients and concentrations obtained by this analysis is also presented. The sensitivity of the analysis to proper background correction is discussed in the light of previous literature and demonstrated experimentally using the well studied Fe(CN)$\sb6\sp{-3/-4}$ system. This technique is used to measure diffusion coefficients and concentrations of benzoquinone (BQ) in a bulk cross linked/quaternized polyvinyl pyridine (QPVP) matrix. The activation energy for diffusion of BQ in the bulk QPVP matrix is determined from temperature resolved studies and are found to be comparable to those obtain for BQ in thin films of QPVP. The enthalpy of partitioning of the BQ into the polymer matrix is also determined. The use of BQ as a probe to obtain in situ film thickness of a thin film modified electrode, consisting of a spin coated QPVP on a gold or glassy carbon electrode, occupies a significant portion of this work. A novel application of the technique to the determination of diffusion coefficients of mobile electroactive species in solid crystalline material is explored briefly. This technique could be generally useful for the measurements of transport coefficients and partition coefficients of electroactive species in polymer electrolytes such as those currently under investigation for rechargeable lithium batteries.Equations for differential pulse voltammetry (DPV) at an ultramicroelectrode are also derived using the split function and excellent agreement with experimental data for a reversible redox couple is demonstrated. High quality approximations to these equations, which could significantly reduce computation time for analysis, are derived along with their range of applicability. Issue Date: 1992 Type: Text Language: English URI: http://hdl.handle.net/2142/23568 Rights Information: Copyright 1992 Barton-Taylor, Marvin Eric Date Available in IDEALS: 2011-05-07 Identifier in Online Catalog: AAI9315949 OCLC Identifier: (UMI)AAI9315949
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