Mechanisms of ionic conductivity for zwitterionic polymers

In this work, ionic conductivity data of zwitterionic polymers are compared with predictions of the random free-energy barrier model for a.c. conduction in disordered solids. It is shown that conductivity follows a long range delocalized diffusion of charge carriers within an equally probable distribution of free-energy barriers. Accordingly, it follows time-temperature superposition, expressed as a master curve for the normalized conductivity as a function of the non-dimensional frequency. The dielectric behaviour is dominated by ionic conductivity, and results suggest a process of quasi-ideal conduction of the ion carriers, consistent with a large value of the dielectric relaxation time characteristic of delocalized conduction processes. It is further remarked that alternative interpretations to the conduction behaviour in these polymers can also be given by other theories and models. (C) 1998 Elsevier Science Ltd. All rights reserved.