含X-型二维液晶基元和反式-4,4′-双(4-羟基苯基偶氮)二苯并-18-冠-6冠醚环的液晶共聚酯的合成与表征

SYNTHESIS AND CHARACTERIZATION OF LIQUID CRYSTALLINE COPOLYESTERS WITH X-SHAPED TWO-DIMENSIONAL MESOGENIC UNITS AND CROWNETHER CYCLES OF trans-4,4′-BIS(4-HYDROXY-PHENYLAZO)DIBENZO-18-CROWN-6

以4,4-′(α,ω己二酰氧)二苯甲酰氯(M1)、2,5-二(对辛氧基苯甲酰氧基)氢醌(M2)和反式4,4′-双(4羟基苯基偶氮)二苯并18冠6(M3)为单体,通过溶液共缩聚反应,合成了一系列含X型二维液晶基元和反式4,4′双(4羟基苯基偶氮)二苯并18冠6冠醚环的主链型液晶共聚酯.共聚酯的分子量不高,[η]在0.37～0.25dL g之间.单体的化学结构通过IR、UV、H NMR、MS和元素分析等方法确证.共聚酯的外观为黄色粉状固体,除CP9外,室温下不溶于CHCl3和THF溶剂.共聚酯的性质采用GPC、[η]、DSC、TG、WAXD和POM等方法进行了研究.发现所有的共聚酯加热到各自的熔融温度以上都能形成液晶态,在液晶态可以观察到近晶相的镶嵌织构或焦锥织构或破扇型织构和向列相的球粒织构或丝状织构或纹影织构.共聚酯的熔融温度(Tm)和各向同性温度(Ti)随共聚酯分子中反式4,4′双(4-羟基苯基偶氮)二苯并18冠6用量的改变呈规律性变化.WAXD研究进一步证实了共聚酯的液晶性.

A series of main chain liquid crystalline copolyesters with X-shaped two-dimensional mesogenic units and crown ether cycles of trans-4, 4＇-bis （4-hydroxyphenylazo）dibenzo-18-crown-6 was synthesized via solution cocondensation polymerizations from 4, 4＇-（ α, ω-hexanedioylxy） dibenzoyl dichloride （ M1 ）, 2, 5-bis （ p- octyloxybenzoyloxy） hydroquinone （ M2） and trans-4,4＇-bis （4-hydroxyphenylazo） dibenzo-18-crown-6 （ M3 ） as the monomers. The molecular weights of copolyesters are not high, and the [ η] of the copolyesters ranges from 0.37 - 0.25 dL/g. The monomer structures were identified by using elementary analysis, IR, UV, ^1H-NMR and MS etc. All the copolyester samples are yellowish powders and insoluble at room temperature in THF and CHCl3 except sample CP9. The properties of copolyesters were investigated by using GPC, [ η], DSC, TG, WAXD and POM. It was found that all the copolyesters went into liquid-crystal phase when they were heated over their melting temperature （ Tm）. In their liquid crystalline state, the typical mosaic texture or focal-conics texture or broken fan texture of smectic phase, and ball granul texture or thread texture or schlieren texture of nematic phase can be observed. Their melting temperature and isotropization temperature （Ti ） changed regularly with varying the trans-4, 4＇-bis （4-hydroxyphenylazo） dibenzo-18-crown-6 unit content in the copolyesters. The WAXD studies also evidenced the liquid crystallinity of these copolyesters.