Thickness-dependent orientation of the pendant phenyl group at the surface of polystyrene thin films

This paper reports on experimental evidence showing that the take-off angle dependence of the photoelectron intensity from the top pi band of a polystyrene thin film, originating from the pendant phenyl group, depends on the film thickness, The result indicates that the orientation of the phenyl group at the film surface changes with the film thickness. Theoretical analysis of the observed angular distribution using the single scattering approximation combined with molecular orbital calculation (SS/MO) showed that the phenyl groups at the film surface become perpendicular oriented ibr a thicker film. The present finding suggests the possibility that the surface property of a thin film of a pendant group polymer can be controlled by changing the film thickness.