Phase separation in PS/PVME thin and thick films

Phase separation in both thin and thick films of polystyrene (PS) and poly(vinyl methyl ether) (PVME) was studied by small-angle laser light scattering (SALLS), atomic force microscopy (AFM), optical microscopy, and X-ray photoelectron spectroscopy (XPS). Blend films with controlled thickness were obtained by spin-coating polymer-toluene solutions with various concentrations. Films with thicknesses smaller and larger than the maximum wavelength of concentration fluctuations were considered. Morphology of the blend films was characterized during and after phase separation. The obtained peculiar morphology was related to surface enrichment with the lower-surface-energy component, as was verified by XPS analyses.