Mobility And Conductivity Of Ions In And Into Polymeric Solids

Abstract

There often has been great uncertainty as to hether typical measurements allo one to conclude that conduction in a given polymer is due predominately to ions or to electrons. Many researchers have assumed that relatively pure polymers can be treated as ide band gap semi-conductors but other scientists have believed that most non-conjugated polymers conduct by the movement of ions. Part of the trouble is that many of the theories predict dependences of current on voltage and sample thickness too similar to easily distinguish between the assumed mechanisms unless extensive and very good data are available. Some comparisons are discussed. More recent approaches that use pressure as an added variable, or those that give careful consideration to such things as gas evolution often allo one to deduce the predominant type of conduction. The concept of local structure of a polymer in the neighborhood of an ion is considered along with the relation of ionic conduction to the entropy correlation theory recently developed by Barker and applied to the case of diffusion in oriented polymers by Barker, Tsai, and illency. According to the evidence, the activation entropy increases under the action of an organizing effect such as uniaxial elongation. Moisture has to important effects on conduction in polymers. At lo concentrations it contributes charge carriers by its on dissociation and at higher concentrations it enhances the dissociation of other ionic species present. Some data for the correlation of conductivity and dielectric constant of solid polymers are discussed in terms of the eak electrolyte model developed by Sharbaugh and Barker for organic liquids. The existence of the correlation seems to imply that many polymers, under most circumstances, are predominantly ionic conductors. © 1976, Walter de Gruyter. All rights reserved.