CHARGE-TRANSPORT MECHANISM IN PRESSED PELLETS OF POLYMER PROTON CONDUCTORS

The charge transport inside some polymer proton conductors, prepared b y chemical doping of poly(propargyl alcohol) and poly(p-diethynylbenze ne) with acids, or by electrochemical polymerisation of thionaphthenei ndole, has been investigated. All the systems, studied as powder press ed pellets between two gold electrodes, show very low electrical condu ctivity due to electrons motion. In presence of environmental humidity the conductivity increases dramatically as a consequence of proton mi gration through the material. A mechanism for the charge transport thr ough the materials, based on the proton conductivity of a thin layer o f acid aqueous solution adherent to the polymer grains, has been hypot hesised. Since the investigated doped polymers show a reversible condu ctivity Variation as a function of water content, they are proposed as materials for humidity sensor construction.