摘要
以１，６－二溴己烷（Ａ）和１，１０－二溴癸烷（Ｂ）为共缩聚单体，按不同摩尔配比与４，４＇－二羟基氧化偶氮苯经相转移催化共聚醚化反应，合成了一系列主链上含有氧化偶氮苯介晶基元的共聚醚，它们均有好的液晶性，其取向膜观察到条带织构，当Ａ／Ｂ的摩尔比为１时液晶态范围最宽。
The monomer having mesogenic moieties based on 4,4'-dihydroxyazoxybenzene has been prepared. There is no evidence for liquid-crystal properties in the monomer,A series of copolyethers with azoxybenzene in main chain were synthesized using the condensed comonomers 1,6-dibromohexane(A)and 1, 10-dibromodecane(B)with different mole ratios by phase-transfer-catalysis copolyetherification reaction with 4,4'-dihydroxyazoxybenzene.Their liquid crystal behavior has been investigated by differential scanning calorimetry (DSC), polarized optical microscopy(POM)with a hot stage and X-ray diffraction techniques, All of the polymers exhibit enantiotropic nematic mesomorphism. The melting temperature and clearing points can be influence by variation of the copolyethers composition.As shown by Figure 1, the region of liquid crystalline phase of the copolyethers was the broadest and its melting temperature was the lowest when the A/B mole ratio is 1. Nematic thread and schlieren textures of polymers were observed. Schlieren textures observed usually by POM for nematic LCP were characterized by two or four dark brushed meeting at a dark point. Banded texture of their oriented films, which of copolyether with mesogenic azoxybenzene has not yet been observed, was obtained as shown by Figure 3. This banded texture, as seen by POM between crossed polarizers, is an optical effect of slight alternating deviations of the molecular chain direction from a fibre axis normal to the bands.
出处
《高等学校化学学报》
SCIE
EI
CAS
CSCD
北大核心
1994年第4期612-615,共4页
Chemical Journal of Chinese Universities
基金
国家自然科学基金
中国科学院高分子物理联合开放实验室(化学所)科学基金
关键词
共聚醚
二羟基
氧化偶氮苯
液晶
Copolyethers,4,4'-Dihydroxyazoxybenzene, Thermotropic liquid crystalline polymer, Banded texture
