The Use of Patterned Polydimethylsiloxane to Control Arrangement of Liquid Crystals

• Main Authors: Ya-Ting Hu, 胡雅婷
• Other Authors: Wenjun Zheng
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/nb8n94

博士 === 國立中山大學 === 光電工程學系研究所 === 103 === Controlling arrangement of liquid crystals plays an important role in manufacturing LC devices. Rubbing polyimide surface which can drive LC molecules to form uniform arrangement is the conventional way to achieve this goal. The grooved structures of polyimide surface caused by rubbing process is regarded as the one mechanism to arrange LC molecules. Therefore, many researches concerning to the effect of surface topological structures to arrangement of LC molecules have been proposed. Polydimethylsiloxane, a silicon-based polymer, is a transparent, flexible and environment friendly material. Besides, the stable physico-chemical properties makes it be popular in many applied area. According to our past studies, nematic liquid crystal molecules can be driven to form homeotropic alignment on polydimethylsiloxane plate surface. Based on the results, PDMS confinement walls are built to confine liquid crystals. The arrangement of liquid crystals will be affect by the four PDMS boundaries. Through varying the depth to width aspect ratio of PDMS confinement structure, the effect of boundaries of PDMS surfaces will be changed. That is, the arrangement mode of liquid crystals will be changed. In this study, imprinting method is involved to produce the PDMS confinement structure. And we find that the arrangement of calamitic nematic liquid crystals will be affected by means of varying the depth to width aspect ratio of PDMS confinement. The aspect ratio is a key factor to obtain different LC arrangement. That is, nematic liquid crystals favor to form planar arrangement as the larger aspect ratio which is greater than 0.4. Otherwise, smaller aspect ratio would make liquid crystals to form vertical arrangement. And for discotic liquid crystals, the PDMS confinement structure can drive the discotic mesogens to form uniform planar arrangement.