Submicrometer-scale heterogeneous surfaces by PS–PMMA demixing

Patterned surfaces were created using two polymers: polystyrene (PS) on the one hand, and either poly(methyl methacrylate) (PMMA) or poly(methyl methacrylate)–poly(methacrylic acid) (PMMA–PMAA) on the other hand. PMMA was dissolved in a solvent of PS; this solution was then spin-coated on a PS support that partially dissolved during the process. The materials were analyzed by water contact angle measurement, XPS, ToF-SIMS and AFM. The effect of the solvent on the final surface morphology was strongly marked. With chloroform, the acrylic polymer was the major surface constituent, possibly because of the high evaporation rate of this solvent. With toluene, which is a better solvent for PS compared to PMMA, the obtained surface was almost exclusively constituted of PS. The use of chlorobenzene provided inclusions of acrylic polymer in PS, both polymers being exposed at the outermost surface. The surface morphology presented rings, the interior of which consisted of the acrylic polymer, while the rest of the surface was made of PS.