AFM/LFM surface studies of a ternary polymer blend cast on substrates covered by a self-assembled monolayer

Nanometer films composed of model ternary blend of deuterated polystyrene (dPS), poly(2-vinylpyridine) (PVP) and poly(methyl methacrylate) (PMMA) were studied after spin-coating from a common solvent. Surface undulations and the distribution of phase-separated domains at the surface and in the bulk are closely related as revealed by atomic (AFM) and lateral (LFM) force microscopy. For the first time the chemical sensitivity of LFM is demonstrated for a ternary polymer mixture. In this case PMMA intercalates between dPS and PVP leading to extended interfaces and surface patterns with two dominant length scales (∼1 μm and ∼100 nm). Both of these length scales as well as the film thickness increase linearly with total polymer concentration in the solvent. Phase separation on two length scales is concluded.