ELECTRICAL-CONDUCTIVITY CHANGES OF POLYMERS WITH CONJUGATED DOUBLE-BONDS INDUCED BY EXPOSURE TO VAPORS AND GASES

Exposure of polyacetylene, polypyrrole, poly(phenylacetylene), and pol y-p-phenylene to oxidizing or reducing gases and vapors leads to chang es of their electrical conductivity which can be explained by a three step model involving as a first step adsorption at the surface, as a s econd step diffusion into the bulk of the material and as a third step irreversible chemical changes due to reaction between the dopant and the polymer chain. These three regimes are sometimes well separated in time. During the adsorption regime, the conductivity change is revers ible with respect to removal of the vapor atmosphere by evacuation.