Synthesis and Properties of Disk-Shaped and T-Shaped Molecules, and Study on Characteristics of Reflective Liquid Crystal Display

• Main Authors: Jui-Yu Yeh, 葉睿祐
• Other Authors: Chiung-Cheng Huang
• Format: Others
• Language: zh-TW
• Published: 2011
• Online Access: http://ndltd.ncl.edu.tw/handle/99888782954140155117

碩士 === 大同大學 === 化學工程學系(所) === 99 === This research is composed of three parts, disc-like imidazolium derivatives, T-shape molecules and reflective liquid crystal displays. In the first part, we synthesized a series of imidazolium derivatives with alkyl different groups on one nitrogen atom and various anions. In the 1H NMR spectrum of compound I5, the broad pattern of C-2 hydrogen is observed at δ 7-8 ppm possibly due to intermolecular hydrogen bonding. Unfortunately, it is thermally unstable and not liquid crystalline. Imidazolium derivatives with alkyl groups on two nitrogen atoms also do not show mesophases possibly due to the effect of curved alkyl chain on lattice arrangement. In the second part, two different T shape molecules by replacing Prof. Yoshizawa’s core biphenyl group with naphthalene group are prepared with different alkyl chain length, to exhibit wider blue phase range than Prof. Yoshizawa’s compounds. However, compound T1’s melting point is below r.t., to possibly due to longer alkyl linkage. In the study of reflective liquid crystal displays, cholesteric liquid crystal materials were obtained by doping compound N2*, N3* and S811 into nematic liquid crystal N4, respectively. The first two exhibit chiral nematic fingerprint texture and no Bragg reflection. S811 (20~30%) doped N4 shows Bragg reflection and chiral nematic planar texture. The driving voltages for bistable state are 8 V and 32 V respectively.