含2,5-□吩熱向型全芳香液晶聚酯之合成與性質之研究

Abstract

含2,5-□吩熱向型全芳香液晶聚酯之合成與性質之研究 研究生 : 黃 興 指導教授 : 莊祚敏 博士 國立交通大學應用化學研究所 摘 要 本研究主要目的是利用2,5-□吩雙□酸合成數系列新型液晶聚酯及液晶共聚酯，芳香二醇部分為4,4‘-聯苯二酚、2,6-二□基□、雙(4-□基苯基)醚、氫□、苯基氫□、□茜。 聚合物是由2,5-□吩雙□酸與芳香二醇以溶液縮合反應聚合而成，縮合試劑為三苯基磷，六氯乙□，□啶，所合成出之液晶高分子是以偏光顯微鏡、微差熱掃瞄卡計、熱重分析儀做定性，本研究將詳加探討分子結構與其物質特性之關係。 單一成分雙醇與2,5-□吩雙□酸所聚合而成的產物中，除了由雙(4-□基苯基)醚與2,5-□吩雙□酸形成的聚合物有向列型液晶相之外，其餘的聚合物都沒有液晶的性質，其原因可能為2,5-□吩雙□酸之紐結構型所導致。 實驗結果顯示:大部分的共聚酯呈現向列型液晶的性質，這種結果可能是由於2,5-□吩雙□酸之紐結構型與芳香二醇之特性所導致。 實驗中所得到的共聚酯熔點分別出現在攝氏202到340之間，極限黏度的範圍分別出現在0.2至0.35(100毫升/克)之間，此結果證明這些聚合物有高的分子量，這一類的液晶高分子具有發展成高性能熱塑性工程塑膠之潛力。

Studies on the Synthesis and Properties of New Thermotropic Main Chain Liquid-Crystalline Wholly Aromatic Polyesters Derived from 2,5- Thiophene Student : Shing Hwang Adviser:Dr. Tzuoh-Miin Juang Institute of Applied Chemistry National Chaio Tung University ABSTRACT (Keyword: 2,5-thiophenedicarboxylic acid, polyester，liquid crystalline polymer) The goal of this study is aimed to synthesized several series of new liquid crystalline polyesters and copolyesters(LCPs) based on 2,5-thiophenedicarboxylic acid , 4,4-dihydroxybiphenyl , 4,4-dihydroxydiphenyl ether , 2,6-dihydroxynaphthalene , hydroquinone , phenyl hydroquinone and quinizarin are used as aromatic diol. Solution condensation of 2,5-Thiophenedicarboxylic acid and corresponding diol were underwent in the presence of triphenyl phosphine, haxachloroethane and pyridine which are used as condensation agents. The synthesized LCPs were characterized by optical polarizing microscope and DSC thermogram. The structure-property relationship of the obtained LCPs is investigated. The results demonstrate that most of the homopolyesters show no liquid crystalline properties. The one synthesized from 2,5-thiophene dicarboxylic acid and 4,4’- Dihydroxydiphenyl ether is the only one which reveals nematic phases. The reason could be due to the kink structure of 2,5-thiophenedicarboxylic acid. The experimental results demonstrate that most of the copolyesters present a nematic liquid crystalline phase. The results could be due to the combination of both kink structures of 2,5-thiophenedicarboxylic acid and aromatic diol. The obtained copolyesters exhibit respectively a melting point ranging from 202-340ºC.Their inherent viscosities range from 0.20 to 0.35dl/g. The results demonstrate that the synthesized LCPs show relatively high molecular weight. The obtained LCPs have potential application in the field of high performance engineering thermoplastics.