Facile fabrication of patterned polymeric films via phase separation-induced surface segregation

Films and surfaces with controlled patterns and features have attracted significant attention due to their widespread engineering applications. In this study, a new strategy based on phase separation-induced surface segregation is proposed. Different molecular chains in a polymer solution moved in different directions. During the segregation process, the molecular chains entangled with each other, hindering each other's migratory behavior, thus forming patterned structure on the surface of the film. Thin films with patterned surface topography were prepared by this method. The results indicate that the surface segregation phenomenon occurs during the film preparation. The surface structure of the films was influenced by the polymer ratio, solution concentration, thickness of the cast film and the solvent volatility. The fabricated films depict ordered topography, containing features with an average diameter of 2.23 mu m when the polystyrene/poly(methyl methacrylate) ratio of 6:1, solution concentration of 10%, evaporation temperature of 30 degrees C, and a cast thickness of 0.1 mm were used. Therefore, based on simple blending combined with surface segregation strategy while optimizing the experimental conditions, patterned films with controlled topology were fabricated with preferred hydrophilic or hydrophobic characteristics. These observations are encouraging for the development of smart engineered surfaces with functional characteristics.