以開環聚合合成鐵電性側鏈液晶聚環氧乙烷和聚環氧丙烷

Abstract

本研究之主要目的在於合成兩系列含旋光基的側鏈液晶聚環氧丙烷與聚環 氧乙烷，所合成的oxetane和oxirane單體是以Borontrifluoride etherate complex為起始劑進行陽離子開環聚合反應，兩系列poloxetane 和polyoxi- rane聚合物分別合成柔軟間距為8至12個亞甲基單位，(2S,3 S)-2-chloro-3 -methylvaleric acid為其末端旋光基，以及biphenyl為 其液晶基的化合物。合成的結果polyoxiranes的分子量比polyoxetanes低 。所有的polyoxe- tanes和polyoxiranes皆呈現層列型液晶行為。間距含 八個亞甲基polyoxe- tane呈現互變型層列A相。間距含九個亞甲基 polyoxetane呈現互變型層列A相和旋光層列C相。然而，十個和十二個亞 甲基間距polyoxetane則呈現互變型層列A相和無法辨認的層列相。間距為 八到十二個亞甲基的polyoxi- ranes皆呈現互變型層列A相和無法辨認的 層列相。研究的結果顯示oxetane和oxirane聚合物有相近的主鏈柔軟性且 不會有側鏈結晶的象現，同時 polyoxetane可以形成旋光層列C相。 The goal of this study is to present the synthesis and characte- rization of two series of side-chain liquid crystalline polyoxe- tans and polyoxiranes. The synthesized oxetane and oxirane mono- mers were polymerized by ring-opening polymerization using boron trifluoride etherate complex as initiator. Both series of poly- oxetanes and polyoxiranes contain eight to twelve methylene units spacers, a (2S,3S)-2- chloro-3-methylvaleric acid chiral end group and a biphenyl mesogen. Polyoxiranes show much lower molecular weight than polyoxetanes. All of the obtained polyoxetanes and polyoxiranes reveal smectic mesomorphism. The polyoxetane con- taining eight methylene units in the spacers present an enantio- tropic smectic A phase. The polyoxetane containing nine methylene units in the spacers reveals enantiotropic smectic A and chiral smectic C phases. While both polyoxetanes containing either ten or twelve methylene units in the spacers display enantiotropic smectic A and undiscriminated smectic phases. Four polyoxiranes containing respectively eight to twelve methylene units in the spacers exhibit enantiotropic a smectic A and an undiscriminated smectic phase. The results demonstrate that the oxetane and oxi- rane polymers have similar backbone flexibility and do not have side-chain crystallization. The polyoxetanes can form an chiral smectic C mesophase.