Characterization of Vertical Alignment Film by X-ray Reflectivity

Depth profile of mass density of vertical alignment film was investigated by X-ray reflectivity, in order to characterize side chains at film for vertical alignment of liquid crystals. Existence thin and low density top layer at surface of polyimide film, which was considered to be side chains, was detected. Furthermore, high density layer about 2 nm in thick just below the top layer was found by X-ray reflectivity. It was also proved that surface treatments both of rubbing and annealing affected the low density top layer and the high density second layer.