玻璃化旋光性層列型液晶合成與鑑定

Abstract

本研究成功的合成出兩種玻璃化旋光性層列型液晶GLC-3H與GLC-2F1H。不同於一般結晶性液晶材料，其低溫下呈現玻璃態而使液晶分子排列特性可保留至固態下。其結構設計以1,3,5-Benzentricarboxylic acid作為核心結構，其上以酯基鍵結層列型懸掛基(smectic pendant)與對掌性懸掛基(chiral pendant)。樣品藉由偏光顯微鏡、示差掃描熱量分析儀以及X-Ray繞射儀進行熱性質的量測與液晶相的鑑定且加以討論。量測結果顯示，兩種液晶的玻璃轉化溫度分別為 25.5 °C與 -4.8 °C，並具有液晶相溫度範圍大於 100 °C 的廣旋光性層列C相(SmC*)；此外，鑑定結果指出兩材料皆呈現Isotropic(I) – Chiral Nematic (N*) – Chiral Smectic A (SmA*) – Chiral Smectic C (SmC*) – Glass (G)之互變型相轉移過程。最後，在層列型懸掛基上以氟原子取代苯環上之側向氫原子的效應亦在此被加以探討。

Novel glassy chiral smectic liquid crystals capable of freezing liquid-crystalline order into solid state without crystallization have been synthesized using 1,3,5-Benzentricarboxylic acid as the core structure to which smectic and chiral pendants are attatched. The mesomorphic properties were verified by using polarizing optical microscope (POM), differential scanning calorimetry (DSC) and X-ray diffractometer (XRD). Both materials possess glassy states with glass transition temperatures below 26 °C and exhibit broader temperature ranges of the chiral smectic C phase (SmC*) than that of conventional ferroelectric liquid crystals. The temperature ranges of the SmC* phase of both liquid crystals are wider than 100 °C with the phase sequence: Isotropic(I)–Chiral Nematic (N*)–Chiral Smectic A (SmA*)–Chiral Smectic C (SmC*)–Glass (G). In addition, the influences of the laterally fluoro-substituent pendants on mesomorphic behaviors were also studied.