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Title: Electrochemical characterisation of indole based conducting polymers
Author: Robertson, Mark Thomas
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1998
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Conducting polymers based on heterocyclic organic systems have found a wide and varied number of applications from fast pH sensors to stealth coatings and drug delivery systems. What is surprising, however, is that very little is known about the actual mechanism by which electrical conduction through these systems occurs. Ac impedance spectroscopy was used along with cyclic voltammetry and rotating disc electrode techniques, to electrochemically characterise polymers formed from indole-5-carboxylic acid (15CA). Physical parameters were obtained from the ac spectra by mathematically modelling the results to a novel transmission line developed during the course of the thesis. Investigations of poly(15CA) have shown that the polymer film undergoes substantial morphological changes on extensive cyclic over the course of a number of weeks. This change has been followed by the used of impedance spectroscopy. It has been found that, on electropolymerisation, the polymer is deposited in compact trimer stacks with extensive π delocalisation occurring between the trimer units. This allows the polymer metallic like conduction with fast electron transfer between the polymer/electrolyte interface and the electrode/polymer interface. These observations have been verified using rotating disc techniques along with Koutecky-Levich analysis. It has been found that there is very little solvent/electrolyte in the film initially. Ac spectra at relatively high potentials (300-500mV) have shown the presence of a kinetic barrier consistent with the injection of positive ions into the polymer pores.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available