| Abstract: | 本研究目的為合成以二酚硫基與二酚碸基為核心架構兩翼皆以酯基連接苯環衍生出六環系統之彎曲形分子。探討隨著尾端烷氧鏈長度變化、苯環上側取代基變化以及利用尾端烷氧鏈碳數不同與單邊側取代造成分子構形上的不對稱，對液晶相造成之影響。
系列一為以二酚硫基核心架構之彎曲形分子，CnS系列在短碳鏈時（n=8、10、12）生成B1相，溫度範圍16-22℃。長碳鏈（n=14、16、18）生成未知相X，溫度範圍6-8℃，施加正向與反向電場時，紋理圖結構沒變但顏色會變化。在最外側苯環上加入氯取代時，CnClS系列，在長碳鏈時（n=12、14、16）會生成鐵電性液晶相B7-like，溫度範圍擴大至55-57℃。外加電場時，紋理圖會生成ribbon，且可以觀察到遲滯現象。
系列二為以二酚碸基核心架構之彎曲形分子，CnSO2系列。在短碳鏈（n=8、10、12）生成B1相，溫度範圍7℃。長碳鏈（n=14、16、18）生成B2相，溫度範圍31-40℃。在最外側苯環上加入氯側取代時，CnClSO2系列，長碳鏈（n=10、12、14、16）會生成未知層相SmX，溫度範圍9-41℃。顯微鏡觀察到fractal紋理圖，X-ray數據證實為簡單層相結構，外加電場下，紋理圖中extinction brush不會偏轉方向，可觀察到三個穩定態，可能為SmCSPA相，還需三角波電場實驗佐證之。不對稱分子CmCnSO2系列以及CmClCnSO2系列，皆生成B2相，溫度範圍分別為23-41℃及44-56℃，尾端烷氧鏈碳數不同與單邊側取代造成分子構形上的不對稱，可以降低液晶相熔點及增加液晶相溫度範圍。將CnSO2系列與CnClSO2系列以比例摻混，在莫耳比例1：1時，為SmX相，混合物C14SO2/C14ClSO2有最低的液晶相形成溫度103.1℃及最大的液晶相溫度範圍58℃。
Novel banana mesogens were obtained by esterification of 4, 4’-thiodiphenol (S) and 4, 4’-sulfonyldiphenol (SO2) with 4-(4-alkyloxybenzoyloxy)benzoic acids (Cn) or 4-(3-chloro-4-alkyloxybenzoyloxy)benzoic acids (CnCl). Variations of the banana mesophases were studied by modifications of the side arms with lateral substituents, and also with unequal length of the terminal hydrocarbons chains.
Bent-shaped molecules derived from 4,4’-thiodiphenol as the central unit. Series CnS, with shorter lengths（n=8, 10, 12）exhibited B1 phase with tempature ranges 16-22℃. On increasing the terminal chain lengths（n=14, 16, 18）, the mesophase changes into the unknown phase X with narrower tempature ranges 6-8℃. Unknown phase X may be switched into the texture with different colours. With lateral chlorine substituent, series CnClS, with longer lengths（n=12, 14, 16）exhibited ferroelectric phase B7-like with broader tempature ranges 55-57℃. On applied voltage, we saw the ribbon texture and hysteresis behaviour.
Bent-shaped molecules derived from 4,4’-sulfonyldiphenol as the central unit. Series CnSO2, with shorter lengths （n=8, 10, 12） exhibited B1 phase with tempature ranges 7℃. On increasing the terminal chain lengths （n=14, 16, 18） , the mesophase changes into the smectic antiferroelectric (B2) phase with tempature ranges 31-40℃. With lateral chlorine substituent, series CnClSO2, with longer lengths （n=10, 12, 14, 16） exhibited unknown smetic phase （SmX） with fractal texture. Tempature ranges are about 9-41℃. Layer structure has be identified by the XRD pattern. SmX phase can be switched, the extinction directions do not change under a field. This phase may be SmCSPA phase, we need triangular voltage experiment to prove it. Asymmetric bent-shaped molecules, series CmCnSO2 and CmClCnSO2, all exhibited B2 phase with tempature ranges 23-41℃ and 44-56℃. With two different terminal alkoxy chains and unsymmetrical substituent groups, can markedly lower melting point and raise tempature ranges. By introducting CnClSO2 into CnSO2, the SmX phase is formed in the mixture with 50％ of CnClSO2 contents. The mixture C14SO2/C14ClSO2 has the lowest melting point 103.1℃ and the broadest tempature range about 58℃. |
