鐵電性液晶環氧乙烷之合成及光聚合研究

Abstract

本研究主要目的係合成在室溫範圍內具有良好排列與旋光層列C相之鐵電性液晶環氧乙烷, 本研究合成兩系列含聯苯酸苯酯液晶基的鐵電性環氧乙烷單體及其側鏈液晶聚合物, 兩系列的差別只在於間距的不同, 以探討不同長度與種類的間距對液晶相與分子排列的影響。第一系列以2與3個重複單位之寡氧乙烯基為間距, 第二系列以4與9個重複單位之亞甲基為間距, 為了比較不同的末端旋光團基對液晶分子自發極化之影響, 本研究分別採用(R)-2-甲基-1-丁醇與(R)-1-甲基-1-辛醇為末端旋光團基, 所合成的液晶化合物皆以熱微差掃瞄卡計、偏光顯微鏡與X光繞射鑑定其液晶相種類與液晶相溫度範圍, 並量測鐵電性液晶單體的自發極化值。研究結果顯示, 本研究所量測到的自發極化值約在40~70 nC/㎝2之間, 所合成之液晶單體只有5M與6M有良好的排列, 經由排列照光聚合後之聚合物分子量均不高, 但其液晶相溫度範圍較其單體寬廣, 甚至含蓋了室溫的範圍。

The goal of this research is to synthesize oriented ferroelectric liquid crystal oxiranes which form a chiral smectic C phase at room temperature. Two series of ferroelectric liquid crystal oxiranes and their side chain liquid crystal polymer was synthesized. In order to study the effect of spacer on the mesogenic phases formed by both monomer and polymer, two different kinds of spacers are used. The first series of monomers contain 2 and 3 oxyethylene units as spacers while the second series of monomers contain 4 and 9 methylene units as spacers. In order to study the influence of different chiral end groups on the spontaneous polarization of the liquid crystal molecules, we employed (R)-2-methyl-1-butanol and (R)-1-methyl-1-heptanol as chiral end group. All synthesized monomers were characterized by differential scanning calorimeter（DSC）, optical polarizing microscope（OM） and X-ray diffraction, and we also test the spotaneous polarization of the ferroelectric liquid crystal monomers. The spotaneous polarization range from 40 to 70nC/㎝2. Among all monomers, only 5M and 6M can be aligned and polymerized, the molecular weights of polymers prepared by in-situ photopolymerization were not high, but their mesogenic temperature ranges were broader than their corresponding monomers。