SOME ASPECTS OF THE RADIATION PROCESSING OF CONDUCTING POLYMERS

Recently, in our laboratory (IARC), complex studies have been made on conducting polymers such as polyaniline, polypyrrole and polythiophene . Our research programme has been directed toward a better molecular u nderstanding of the structural properties controlling electronic condu ctivity of polymers. The most important issue of our studies within co nducting polymer family includes effect of gamma and electron beam irr adiation on their electrical conductivity. The irradiation was perform ed on the samples in the form of pellets onto which aluminium electrod es had been vacuum-deposited. The relative conductivities of irradiate d pellets prepared from highly conducting polyaniline, polypyrrole and polythiophene powders decreased with increase of irradiation dose und er vacuum. On the other hand in the case of irradiation under dopant a tmosphere conductivity of pellets was increased. The dramatic increase in conductivity was observed after irradiation of insulating polyanil ine form (even under air atmosphere). The ESR studies suggest that the charge-transport in low doped conducting polymer can be explained by paramagnetic polaron migration along and between the polymer chains. A t higher doping levels, in the case of polythiophene and polypyrrole t he energetically favourable is a bipolaron state as charge carrier.