Investigation on the surface orientation of cylindrical microdomains in styrene-butadiene-styrene triblock copolymers by scanning force microscopy/transmission electron microscopy

摘要

The orientation of the microdomains at the free surface of solvent-cast films of a polystyrene-block-polybutadiene-block-polystyrene triblock copolymer with cyclindrical morphology was studied by coupling transmission electron and scanning force microscopies (SFM-TEM). It was found that the cylinders of polystyrene, which are assembled in grains randomly oriented in the bulk, tend to reorient with the main axis perpendicular to the surface. SFM investigation indicates that the hexagonal symmetry of the cylinders is also maintained at the free surface which is characterized by protrusions and corrugation with size and characteristic distances closely related to the cylindrical morphology visible in the bulk. Good quantitative agreement between TEM and SFM measurements is observed.