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Title: Studies on conducting polymers
Author: Mohammad, F.
Awarding Body: University of Sussex
Current Institution: University of Sussex
Date of Award: 1987
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This thesis reports studies of several aspects of the behaviour of intrinsically conducting organic polymers with conjugated backbones. Polyparaphenylene has been synthesised by a range of chemical methods and the products studied by spectroscopy, x-ray diffraction and electrical properties. It is shown that the properties of the polymer are sensitive to the method of synthesis. The intrinsic and oxidative degradation of compensated and p-type doped poly thiophene and polypyrrole have been studied by uv-vis, ftir, tga and by monitoring electrical conductivity. Dissimilar degradation behaviours of the two polymers have been rationalised in the light of the ionisation potentials of the polymers and the chemical nature of their repeat units while comparing with other polymers such as polyacetylene, polymethylacetylene and polypropylene. Studies on poly thiophene and polypyrrole show that these polymers are much more stable than polyacetylene but still undergo degradation reactions which involve two steps viz. loss of dopant and then degradation of polymer backbone. The general features of their degradation mechanisms are discussed. Thin films of p-type doped poly thiophene were found to react ~apidly but irreversibly with ammonia and water whereas the loss of conductivity was largely reversible by evacuation in polypyrrole. The interaction between compensating agents such as ammonia, water and butyl lithium with p-type doped poly thiophene and polypyrrole has been examined and chemical reaction schemes have been proposed with a possiblility of their use in sensing devices. The diffusion of dopants into and out of poly thiophene and polypyrrole along with its dependence on temperature and dopant concentration in the polymer, has been studied by a galvanostatic pulse method. The Arrhenius plots show two distinct but fairly linear regions of low and high activation energies with a transition at 273K. An increase in diffusion coefficients in the order of N(But)4+ BF4-
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Polymers and conduction Chemistry, Organic Chemistry, Physical and theoretical