| Popis: |
The aim of the work presented in this thesis is to investigate novel conducting polymers and copolymers, derived from indole and substituted indoles. Particular emphasis has been given to the study of the electropolymerisation mechanism, the structural characterisation of the deposited layer and possible applications as electrochemical sensors. The redox and morphological properties of the electrochemically deposited polymer layers have been investigated with regard to the steric and electronic effects induced by varying the substituent. The use of substituents to enhance polymer solubility has also been addressed. In particular, a thorough investigation of poly(indole-5-carboxylic acid), poly(5-cyanoindole) and poly(indole) has been undertaken. The major component in the deposited layer has been identified as an asymmetric trimeric unit and has also been identified as the main repeat unit within the polymer. Furthermore, the formation of this trimeric unit is believed to be general to all the indole based conducting polymers studied. The trimeric units and larger oligomers/polymers have been characterised electrochemically and spectroscopically. The polymerisation mechanism has been postulated and has led to the production of a reproducible polymer layer. The electropolymerisation of novel polymers produced by the copolymerisation from a mixture of two substituted monomers has also been investigated. Copolymerisation has resulted in the formation of bifunctional trimer units which have been chromatographically separated and characterised individually by both electrochemical and spectroscopic methods. Potential applications of this type of polymer are as sensors. Several polymers and copolymers have been studied in an aqueous electrolyte, with the electrochemical response being measured as a function of the electrolyte pH. The effect of adding metal ions to the electrolyte medium on the measured potential has also been studied. The data suggest the possible use of these functionalised polymers in simple electrochemical sensor systems. |
