合成新型大傾斜角具廣溫度範圍之強誘電性液晶

Synthesis and Characterization of Novel Ferroelectric Liquid Crystalline with a Large Tilt Angle and Wide Temperature Range

本文在研究強誘電性行為的低分子量有機矽氧烷液晶材料。設計並合成一末端基上含寡聚物矽氧烷，並且結構核心為4-hydroxyphenyl 4'-hydroxybiphenyl-4-carboxylate 與chiral octan-2-ol unit 的液晶。此新型大傾斜角液晶具有廣泛旋光性C 型層列 （chiral smectic C, SmC*） 的溫度範圍，並藉由實驗鑑定出SmC*相。此SmC* 液晶相鑑定藉由正交偏光顯微鏡 （polarizing optical microscope,POM）、示差掃描熱量分析儀 （differential scanning calorimetry, DSC） 和X 光繞射分析儀 （X-ray diffractometer, XRD） 等光學儀器來測定液晶相特性，發現所設計液晶澄清點有下降的趨勢。

The present paper is a study of the ferroelectric behavior in low molarmass organosiloxane liquid crystal materials. We have achieved the moleculardesign, synthesis and characterization of liquid crystals which have4-hydroxyphenyl 4'-hydroxybiphenyl-4-carboxylate cores, chiral octan-2-olunits and oligomeric siloxane end-groups. A few novel compounds withlarge tilt angles and wide temperature ranges of SmC* phase have beensynthesized, and the mesophases have been compared.The characteristics of the liquid crystal phases under discussion wereinvestigated by means of polarizing microscopy, differential scanningcalorimetry, X-ray diffraction and electro-optical experiments. The influenceof the molecular structure on the occurrence of the SmC* phasewas investigated. These substituents have a strong influence in reducingclearing temperatures and increasing temperature ranges.