Control of Pretilt Angle in Liquid Crystal and Photocurable Monomer System

초록

The pretilt angles of liquid crystals (LCs) could be controlled over the range, 0(o) to 90 degrees, using LC/photocurable monomer (NOA65) mixture system through UV irradiation. The pretilt angles could be controlled using LC/NOA65 mixture in planar polyimide coated LC cell, by changing the mixture ratio ranging from 99.9/0.1 to 99.0/1.0 and UV irradiation time (10 and 20min). Planar and tilted alignment was observed in LC/NOA65 mixture of 99.9/0.1 and 99.8/0.2, respectively, after UV irradiation for 20min. Finally, homeotropic (or vertical) alignment was observed in weight ratio of over 99.7/0.3. The LC alignment behavior was well correlated with the wettability of the alignment films due to the surface morphology on the alignment layer surfaces by photopolymerization-induced phase separation. This study contributes to the latest efforts to develop new method for pretilt angle control.

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