Abstract
Liquid crystals’ surface morphologies, molecular reorientation, alignment, and nematic pretilt angles on polyimide surfaces were studied. The polyimide molecules contained cinnamoyl side groups; they were treated by irradiation with linearly polarized ultra-violet light or rubbing. Root-mean-square surface roughnesses over 1.0 μm × 1.0 μm areas were 0.282, 0.260, and 2.073 nm for untreated, irradiated (1.0 J/cm2), and rubbed (strength, 65 cm) films, respectively. The optical axis of the irradiated film was perpendicular to the light's direction of polarization; in the rubbed film it was parallel to the rubbing direction. Rubbing resulted in higher retardation than irradiation. The orientations of liquid crystal molecules on the films coincided with their polymer chain orientations. Fabricating LC cells with rubbed film resulted in higher pretilt angles than using irradiated film.
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