| Summary: | 碩士 === 逢甲大學 === 化學工程學所 === 99 === Various soluble polyimides (PI) which can act as homogeneous or homeotropic alignment films are synthesized in this study. Homeotropic PI was synthesized by grafting alkyl side chain on the backbone of homogeneous PI. The molecular structures were adjusted by changing the grafting density and the length of the side chains. These PIs were used as alignment layers for the fabrication of LC cell. The pretilt angle of liquid crystal (LC) molecules was measured. Effects of the conformation of the PI molecule on the thermal stability, surface energy, surface morphology, and pretilt angle of the PI film were investigated. We also study the influence of the rubbing depth on the surface properties of the rubbed PI layer and the pretilt angle properties of the alignment films. The alignment properties can be tuned by adjusting rubbing depth, together with the grafting density and the length of the side chains. In addition, various homogeneous and homeotropic PIs were blended by different ratio to adjust the pretilt angle of the alignment film. The alignment film with 75o pretilt angle and the dual frequency liquid crystals were used to make a new type of display. The feasibility of using the display for bistable display applications was investigated.
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