Relation between molecular orientation and rubbing strength observed by reflection ellipsometry

The relation between polyimide molecule orientation and rubbing strength (RS) is studied using reflection ellipsometry, and the film structure is considered to be different above and below an RS of 2.2 mm. Above 2.2 mm, the ordering of polyimide increases sharply in the weakly rubbed condition, and then saturates. The tilt angle of the principal dielectric axis of the molecule-oriented layer also increases very sharply to 53 degrees and then monotonically decreases to 39 degrees. However, no marked RS dependence is observed in the thickness of the molecule-oriented layer.