Based on comprehensive studies by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) we report on the morphology and the ion–ion as well as the ion–polymer interaction properties of thin spin-cast films comprising an oligo(ethylene oxide) (OEO) grafted poly(p-phenylene) blended with either lithium- or tetrabutylammonium trifluoromethanesulfonate. Assuming that the ionic species intercalate within the OEO side-chain matrix, the covalent attachment of OEO appears to be an appropriate strategy to overcome the generally observed phenomenon of large-scale phase-separations between conjugated polymers and solid-state electrolytes. XPS turns out to be a suitable approach to study the basics of the ion–ion and the ion–polymer interactions of these model systems directly for the thin, spin-cast films.