Synthesis, characterisation and application of micro/nano structure conducting polymers

Conducting polymer micro/nanostructures have recently received great attention because of their long conjugation length, high surface area and promising applications in a variety of fields. At the same time, fabrication of micro/nanostructures of conducting polymers with controlled morphology and size remains a challenge for Chemists and Materials Scientists. The focus of this thesis, therefore, is to develop novel conducting polymer micro/nanostructures with a well defined morphology and to consider their potential for applications as sensor and actuating elements. In each case, the structure, conductivity and electrochemical properties of the conducting polymer nanostructures have been characterized using FTIR, Raman, UV-vis, XPS and elemental analyses, conductivity measurements and cyclic voltammetry. Hollow nanospheres of substituted polyanilines (PANI) were fabricated chemically using ammonium persulfate as the oxidant in the presence of a polymeric acid poly(methyl vinyl ether-alt-maleic acid) (PMVEA). The effects of chemical reaction conditions, including the weight ratio of monomer to PMVEA, concentration of monomer, the molar ratio of monomer to oxidant, the reaction temperature and the type of the monomer, on the formation of hollow nanospheres were systematically studied. The weight fraction of PMVEA to monomer is particularly important for determining the size and uniform shape of the substituted PANI hollow spheres. The formation mechanism for the hollow nanospheres was studied in detail for the case of poly (o-methoxyaniline). The hollow nanospheres were used to construct a simple electrochemical oligonucleotide (ODN) sensor, where ODN probes were covalently grafted onto the residual carboxylic acid functionalities of the hollow nanospheres. Abstract II Poly(3,4-ethylenedioxythiophene) (PEDOT) hollow microspheres ranging from 0.5 to 10 ??m in diameter were synthesized by chemical oxidative polymerisation of EDOT using ammonium persulfate in a catanionic surfactant solution, obtained by mixing cetyltrimethylammonium bromide (CTAB) and sodium dodecylbenzenesulfonate (SDBS). The effects of chemical reaction conditions, including the molar ratio of CTAB to SDBS, the concentration of total surfactants, the type of oxidant and magnetic stirring, on the formation of the PEDOT hollow microspheres were investigated systematically. The formation of PEDOT hollow spheres is presented as following a vesicle-templating mechanism, supported by Freeze Fracture TEM results. Moreover, the PEDOT hollow spheres showed a more effective electrocatalytic activity for the oxidation of ascorbic acid, compared to conventional PEDOT granular particles, which were also effective in lowering the ascorbic acid oxidation overpotential. By extending vesicle-template method into the electropolymerisation of polypyrrole (PPy) films with para-toluene sulfonate (pTS) as the main dopant, a novel micro ring structured surface morphology was prepared by using CTAB/SDBS vesicles as templates. Spectroscopic characterisations confirmed that the…