含反式環己烷液晶基之側鏈液晶聚環氧乙烷和聚甲基丙烯酸酯之合成

Abstract

本研究之主要目的是探討高分子主鏈對於所合成聚合物液晶相之影響，總 共合成了兩系列含反式環己烷之環氧乙烷及甲基丙烯酸酯之側鏈液晶聚合 物，第一系列的環氧乙烷化合物是以Boron trifluoride etherate作為起 始劑，進行開環聚合反應，而第二系列的甲基丙烯酸酯化合物則是以 AIBN作為起始劑，進行自由基聚合反應。所合成之本系列環氧乙烷單體具 有較短之柔軟間距者呈現雙變型向列型液晶相，具有較長柔軟間距者( n=9 )則呈現雙變的向列相和單變的層列B相，至於甲基丙烯酸酯單體，柔 軟間距較短者(n=3,4,5,6)呈現單變的向列相，柔軟間距較長者(n=11)則 出現互變的層列A相。所合成的聚環氧乙烷皆具有液晶行為，間距較短者( n=1, 2)只呈現一個互變的層列A相，含3個或4個亞甲基間距者則呈現一互 變的向列相和兩個層列相，至於含最長間距者(n=11)則呈現三個互變的層 列相，所合成之聚甲基丙烯酸酯皆呈現層列型液晶相，間距較短者( n=3,4,5)只出現一個層列相，至於間距較長者(n=6,11)則出現兩個層列相 。研究結果顯示高分子主鏈的柔軟度不但對液晶相溫度範圍有影響，對於 液晶相之種類也會有影響，較柔軟之聚環氧乙烷具有較寬的液晶相範圍， 同時也具有較多及較規則之層列相。 The goal of this research is to study the effect of polymer ne on the mesomorphic properties of the side-chain liquid crystalline polymers.Two series of side-chain liquid crystalline polyoxiranes and polymethacrylates containing 4-alkanyloxyphenyl trans-4-pentylcyclohexanoate side groups are prepared.The poly- oxiranes are synthesized by ring-opening polymerization of oxi- rane monomers using boron trifluoride etherate as an initiator. The polymethacrylates are synthesized by free-radical polymeriz- ation of methacrylate monomers using AIBN as an initiator.All of obtained oxirane monomers present an enantiotropic nematic phase .The oxirane monomer which contains 9 methylene units in the spacers is the only one exhibits a monotropic smectic B phase besides the nematic phase. The methacrylate monomers containing short spacer length( n=3,4,5,6) show an monotropic nematic phase, while the methacrylate monomer containing a longer spacer length (n=11) reveal an enantiotropic smectic A phase.All of the obtained polyoxiranes and polymethacrylates present liquid crystalline phases.The results demonstrate that the flexibility of the polymer backbone will affect not only the mesomorphic temperature range but also the nature of mesophases formed.The polyoxirane backbone is more flexible than polymethacrylate backbone.Therefore,the prepared polyoxiranes show a wider tempe- rature of mesophase and exhibit more ordered smectic phase than the polymethacrylates.