二元液晶的物理與元件特性

Physical and Device Characteristics of a Binary Liquid-Crystal Mixture

林若彧(Ruo-Yu Lin)

指導教授 ： 李偉

中原大學/理學院/物理研究所/碩士(2010年)

https://doi.org/10.6840/cycu201000690

摘要

本研究旨在探討負型液晶摻入正型液晶混合溶液的物理特性，研究內容包括相轉變溫度、複折射率、介電異方性以及旋轉黏滯係數隨負型液晶添加濃度的改變；此外，本論文也探討不同含量比之二元液晶元件的反應時間，期望能藉由調整負型液晶的比例，達到調控混合物材料與元件特性的目標。
在實驗結果中，吾人發現以負型液晶為添加物摻進正型液晶，隨添加濃度的提升，其相轉變溫度有明顯改變，包括結晶點溫度下降、澄清點溫度上升，液晶相之溫度範圍更加寬廣。由於負型液晶之添加，複折射率值略低；若液晶混合物所含負型液晶濃度越高，則二元液晶複折射率也下降至接近負型液晶複折射率之值。並且我們也在測量不同溫度下各樣品物性改變的實驗中，觀察到各樣品因負型液晶濃度不同，溫度對介電異方性與旋轉黏滯係數的影響亦不相同。最後在反應時間的實驗結果中，清楚觀察到由於負型液晶濃度提高，造成反應時間增加，而且其上升形式為一指數函數。

關鍵字

旋轉黏滯係數 ； 相轉變溫度 ； 反應時間 ； 介電異方性 ； 複折射率 ； 秩序參數 ； 液晶 ； 二元 ； 混合物

並列摘要

This research focuses on physical properties of binary mixtures containing a major positive liquid crystal and a minor negative one. The physical characteristics investigated include the phase-transition temperature, birefringence, dielectric anisotropy, and the rotational viscosity. In addition, the response times of the devices made of various mixtures with distinct content ratios have also been studied. Many material and device properties of the binary mixture can be tunable by changing the compositional ratio of the two liquid-crystal components.
The experimental results show that the phase-transition temperatures are altered when the major liquid crystal is blended with the negative liquid crystal. The changes include the decrease in the melting point, increase in the clearing point, and, in turn, the wider range of the mesophase. The birefringence of the binary liquid crystal decreases with increasing concentration of the negative-liquid-crystal component because the birefringence of the negative dielectric anisotropy is less than that of the positive one. The physical properties of the binary substance, such as the dielectric anisotropy and rotational viscosity, change at various temperatures. Furthermore, the response time of the blend rises exponentially with the increase in concentration of the liquid crystal with negative dielectric anisotropy.

並列關鍵字

dielectric anisotropy ； mixture ； binary ； liquid crystal ； order parameter ； rotational viscosity ； response time ； phase-transition temperature ； birefringence

參考文獻

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