Effects of secondary doping on the conductivity of polyaniline and its blends

Hadavinia, Homa, Foot, Peter, Barton, Stephen and Farid, Ahmed S. (2012) Effects of secondary doping on the conductivity of polyaniline and its blends. In: 6th International Conference on Advances in Computational Engineering & Experimentation; 01 - 04 Jul 2012, Istanbul, Turkey. (Unpublished)


The doping process is a unique and unifying theme which distinguishes conductive polymers from all other polymer types. In conducting polymer field, dopant is a substance which causes electronic, optical, structural changes of polymers. Doping process can be classified in two common forms which are redox doping and acid/base protonic acid doping. Oxidizing or reducing agents remove or add electrons from or to the polymer backbone if redox doping is preferred. Acid/base protonic acid doping is another doping process whereby electron numbers remain the same. Both of these doping types can be referred as primary doping which will lead changes of the original properties of the non-doped polymer. Secondary doping of a conducting polymer is done with an apparently inert substance when applied in the form of liquid or vapour to polymer which is already doped by a primary dopant. Secondary doping process causes high conductivity in the conducting polymer such as polyaniline and other polymer systems. This process induces significant changes in molecular conformation, crystallinity, conductivity, electronic, optical and structural properties of polymers. Effects of secondary doping of polyaniline (PANI) blends, prepared by emulsion polymerization of aniline in the presence of sulphuric acid (H2SO4) and epichlorohydrin (ECH) rubbers on conductivity, mechanical properties was investigated. Secondary dopant in this study was chosen from phenolic compounds such as m-cresol, p-cresol, 2-Cl-phenol. Contacting of polyaniline in the forms of gelatinous state, thin films, pellets and powder with phenolic compounds is an effective ways of secondary doping process. The effects of secondary dopant persist after complete removal of the secondary dopant while it will induce an increased conductivity of PANI. PANI and its blends are also characterized using thermogravimetric analysis (TGA), infrared spectroscopy (IR) and scanning electron microscopy (SEM).

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