Use this URL to cite or link to this record in EThOS:
Title: Synthesis and electronic properties of novel conducting polymers
Author: Spearman, Peter
ISNI:       0000 0001 2413 217X
Awarding Body: Kingston University
Current Institution: Kingston University
Date of Award: 1995
Availability of Full Text:
Access from EThOS:
Access from Institution:
In this work, some derivatised polyanilines have been synthesised in order to evaluate their electronic properties with respect to the parent polymer. Substitution of the ring at the 2- position permitted polymerisation to take place whereas substitution at the 3-position caused steric hindrance and disfavoured polymerisation. Solubility of the polymer was increased according to the length of the chain substitution, however, at the expense of its conductivity. A condensation route was adopted to synthesise regioregular polyanilines unambiguously linked at the para-position. Reaction of appropriate monomers led to the production of polyanilines that were closely related to an octamer of polyaniline rather than a polymer. A series of polyquinoxalines and model oligomers were synthesised and analysed in order to characterise the trend in their properties up to the polymer stage. Synthesis of the polymer by condensation technique led to a moderately conductive material that was highly insoluble and unprocessible. Precursor techniques improved processibility but the final materials remained uncharacterisable. To address this problem, short chain oligomers of the parent compound were systhesised. The five-ring member of the series (L5) exhibited a complex redox behaviour akin to polyanilne, that was analysed using cyclic voltammetry and in situ spectroelectrochemical techniques. Vacuum evaporated thin films of L5 underwent two stages of reduction in acid media via an intermediate highly conductive plateaux region. This region was probed using ac voltammetry and in-situ ESR measurements. Discussion of the various neutral and protonated forms is supported by theoretical calculations that used MNDO techniques to determine such parameters as their ionisation potentials, dipole moments and heats of formation. Their ground state geometries were also determined by analysis of bond charge distributions. Fast electrochemical switching times of the order of 2 ms between redox states were achieved and accompanied by highly contrasting colour changes according to redox potential. The synthesis of seven ring and nine ring quinoxalines appeared to be successful but they could not be vacuum evaporated at pressures of 10-6 Torr.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Chemistry