Surface morphology and properties of ternary polymer blends: effect of the migration of minor components.

In this work, the surface morphology and properties of ternary polymer blends and the migration of minor component molecules to the top surface layer of the films were studied. We used polystyrene (PS), poly(butylene adipate-co-terephthalate), polycaprolactone, poly(methyl methacrylate), and polylactide as second minor phases in a blend of polyethylene terephthalate-poly(ethylene glycol) (PET-PEG). The morphology of the ternary systems predicted using the spreading coefficient and relative interfacial energy concepts was confirmed by scanning electron microscopy images. The surface characterization results showed a higher rate of migration of PEG to the polymer-air interface in the systems with a nonwetting morphology and the highest in the PET-PS-PEG blend. Atomic force microscopy images suggested that the high surface hydrophilicity of the PET-PS-PEG blend is due to a dendritic pattern of PEG crystals on the film surface, which were not observed for the other samples.