Dielectric Measurements of Polymer Electrolyte Based Composites as a Technique for Evaluation of Membrane Homogeneity

Three series of composite proton exchange membranes containing SiO2 as filler were prepared and studied by a.c. impedance spectroscopy. Cast membranes were based on SPEEK and Nafion polymers and one more series was obtained by Nafion impregnation via sol-gel technique. This reaction was carried out under equilibrium conditions at long diffusion time with pre-defined water and TEOS contents as a given ratio per -SO3H group. The study of electro-physical properties of composite membranes showed that the dielectric permittivity, measured using a simple probing device in different locations of a composite film, may be used not only for structural and electro-physical characterization of the materials but also as a parameter allowing to estimate homogeneity and spatial uniformity of the membranes.