藍相液晶合成與鑑定

Abstract

本研究主要目的為合成旋光性化合物，與液晶混合物混合後誘導出藍相液晶。第一部分合成出五種旋光性化合物，以酯基做為連接基。其中三種化合物結構為長碳鏈上有旋光性甲基取代基，具有較小的HTP (helical twisting power)。化合物1M及3M 含有4-[(4-[(1R)-1-methylheptyl]oxybenzoyl)oxy] benzoic acid。1M~3M皆為膽固醇液晶相，液晶相溫度範圍分別為-10~30 oC、25~98 oC、86~240oC。其中2M成功出現藍相BPIII*，藍相溫度範圍達25 oC。而其餘兩種化合物以具光學活性的雙環結構做為中間連接基呈對稱性結構，得到較大的HTP，但無液晶相。 第二部分將實驗中合成之化合物與商業用nematic液晶混合，依據不同混合配方與比例得到藍相結構。其中化合物3M和host NCTU-2混合後得到90 oC寬溫並為BPIII*結構。我們發現本實驗合成之化合物成功出現藍相，並經由混合後更得到寬廣藍相範圍，相信有機會應用於新一代藍相液晶顯示器中。

The goal of this study is aimed to synthesize chiral dopants which are mixed with liquid crystals to induce blue phase liquid crystal. The first part of this study, we synthesized five chiral dopants based on ester group. The three compounds contain chiral group-methyl substituted on alkyl chain. They have low helical twisting power (HTP). Both 1M and 3M contain 4-[(4-[(1R)-1-methylheptyl]oxybenzoyl)oxy] benzoic acid . All of three monomers 1M~3M exhibit cholesteric phase. The cholesteric temperature range of 1M~3M are -10~30 oC, 25~98 oC, 86~240 oC, respectively. Monomer 2M exhibits a blue phase BPIII* over a temperature range more than 25 oC. Both monomer 4M and 5M containing isosorbide group show no mesomorphic behavior. They are high HTP. The second part of this study the chiral dopants are mixed with eutectic mixture to study the formation of blue phase. The results indicate that depend on different proportions can be successfully induced blue phase. The chiral dopant 3M mixed with host LC NCTU-2 can induce a blue phase BPIII* which cover a wide temperature range of 90 oC. In this study, we formulate several mixtures which exhibit wide temperature range of BPIII*.They have potential applications in BPLC display.