Relaxation phenomena and conductivity mechanisms in anion-exchange membranes derived from polyketone

A polyketone-b-poly[N-(4 methyl-methylpyridium)-ethylenepyrrole(+)][X-], with X- = I- or OH-, is investigated as an example of anion-exchange membrane with potential applications in fuel cells. The polyketone starting material PK and the functionalized polyketones Pyr-FPKmI and Pyr-FPKmOH are investigated via Broadband Electrical Spectroscopy (BES) to understand the conductivity mechanism. BES signals are collected in the frequency range of 10(-2) - 10(7) Hz and from -100 degrees to 120 degrees C. BES measurements reveal the presence of up to three interdomain polarizations phenomena, one electrode polarization event and two beta dielectric relaxation modes for both wet Pyr-FPKmI and Pyr-FPKmOH. Ion conductivity for Pyr-FPKmI and Pyr-FPKmOH is found to be 0.0086 and 0.0105 S cm(-1) at 80 degrees C, respectively. The overall conductivity mechanism is attributed to the superposition of two conduction pathways, via delocalization bodies and via interdomain percolation pathways, which are associated with two different physical phenomena. (C) 2019 Published by Elsevier Ltd.