INVESTIGATION ON THE SURFACE ORIENTATION OF CYLINDRICAL MICRODOMAINS IN STYRENE-BUTADIENE-STYRENE TRIBLOCK COPOLYMERS BY SCANNING FORCE MICROSCOPY TRANSMISSION ELECTRON-MICROSCOPY

The orientation of the microdomains at the free surface of solvent-cas t films of a polystyrene-block-polybutadiene-block-polystyrene tribloc k copolymer with cyclindrical morphology was studied by coupling trans mission electron and scanning force microscopies (SFM-TEM). It was fou nd that the cylinders of polystyrene, which are assembled in grains ra ndomly oriented in the bulk, tend to reorient with the main axis perpe ndicular to the surface. SFM investigation indicates that the hexagona l symmetry of the cylinders is also maintained at the free surface whi ch is characterized by protrusions and corrugation with size and chara cteristic distances closely related to the cylindrical morphology visi ble in the bulk. Good quantitative agreement between TEM and SFM measu rements is observed.