Evidence for clustering in<i>N</i>‐butyl methacrylate ionomers as shown by thermally stimulated currents

Abstract

Abstract The relaxation behavior of n ‐butyl methacrylate/methacrylic acid (MAA) copolymers (12 mol % MAA) and their alkaline salts (K, Li) with various degrees of neutralization was investigated from 77 to 400 K by means of thermally stimulated depolarization and polarization methods. For degrees of neutralization higher than 50%, the experimental results were found to be consistent with the existence of complex heterophase structures involving significant widening of the distribution function of relaxation times in the glass transition region, splitting of the side‐chain transition in several discrete relaxation components, and formation of ionic cluster giving rise to their own relaxation process. By systematically studying the influence of polarization conditions, it was also shown that the appearance and stability of such clusters are markedly dependent on the thermal and electrical history of the samples and that the clustering relaxation is closely related to the ionic conductivity via space‐change formation.