Atmospheric dielectric barrier (silent) discharge modification of polystyrene/polycarbonate immiscible polymer blend surfaces has been studied by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Localized Variations in the level of treatment across the surface are evident which can be correlated to the spatial distribution of the respective blend constituents, Subsequent washing of low molecular weight oxidized material from the treated surfaces leaves behind well-defined terraces/wells whose size can be tailored by changing the original polymer blend composition.