Intrinsically conducting polymers

Sabagh, Basseem (2007) Intrinsically conducting polymers. (PhD thesis), Kingston University, .


The synthesis, properties optimisation and blending of two intrinsically conducting polymer families have been investigated. Electron rich polymers, based on polythiophene derivatives, and electron deficient polymers, based on polypyridine derivatives, were successfully synthesised and characterised. Poly (3,4-ethylenedioxythiophene) [PEDOT] was synthesised by controlled oxidative polymerisation. Hexyl-substituted EDOT, which is commercially unavailable, was successfully synthesised via an eight step reaction. Poly (3-nitropyridine) [PPy-3-NO[sub]2] was produced following a revised literature method. The synthesised polymers were then blended together in a 1: 1 monomer ratio. A search for evidence of charge transfer between the blended polymers was carried out using several techniques. UV-Visible spectroscopy showed signs of an increase in the extent of conjugation due to charge transfer. ESR measurements showed a large increase in the concentration of unpaired electrons in the blends. Cyclic voltammetry was employed to study the electrochemical behaviour, and revealed that the charge transfer caused the polymers in the blend to oxidise and reduce differently from the pure polymers. Finally, electrical conductivity measurements indicated an increase in the bulk conductivity when blending the polymers together reaching, in some cases, up to two orders of magnitude.

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