Polyimide, Polyamide-Imide and Polyamide Alignment Layers for Antiferroelectric Liquid Crystal Display Cells and Their Structural Effect on Hysteresis Behavior

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Abstract
Polyimide, polyamide-imide and polyamide alignment layers for antiferroelectric liquid crystal cell devices were developed. Good quality alignment with improved electrooptical properties of the cell was observed by using structurally different fluorine and non-fluorine containing polymers as surface alignment layers. The double hysteresis loops characteristic of the antiferroelectricity arising from the chiral smectic phase were found to be different depending on the different molecular structure of polymer alignment layers. The switching between antiferroelectric (AF) and ferroelectric (F) states significantly depended on the molecular structure of the alignment layer and liquid crystals used. The liquid crystal blend (AFLCB-1) used in the experiment exhibited a wide temperature range of the smectic C*A phase. In the present paper, we report the broader hysteresis with higher driving margin for the non-fluoro polymer alignment layers as compared to those of the fluoro polymer aligning layers under identical conditions. The driving margin (M) varied from the 0.21 to 2.2 as the alignment layers were changed in the cells. All the alignment layers developed in our laboratory showed superior properties to that of the commercially available alignment layer material (LQ-1800).