含X-型二维液晶基元和顺式-4,4′-双(4-羟基苯基偶氮)二苯并-14-冠-4冠醚环液晶共聚酯的合成与表征

Abstract

以4,4′-(α,ω-辛二酰氧)二苯甲酰氯(M1)、2,5-二(对十二烷氧基苯甲酰氧基)对苯二酚(M2)和顺式-4,4′-双(4-羟基苯基偶氮)二苯并-14-冠-4(M3)为单体,通过溶液共缩聚反应,合成了一系列含X-型二维液晶基元和顺式-4,4′-双(4-羟基苯基偶氮)二苯并-14-冠-4冠醚环的主链型液晶共聚酯.单体1(M1)由对羟基苯甲酸和辛二酰氯,通过酯化和取代反应制备,单体2(M2)由2,5-二羟基苯醌和对十二烷氧基苯甲酰氯通过酯化和还原反应制备,单体3(M3)由顺式-二氨基二苯并-14-冠-4和苯酚通过重氮化和偶联反应制备.共聚酯的分子量不高,[η]在0·35~0·25dL/g之间...

A novel series of main chain liquid crystalline copolyesters with X-shaped two-dimensional mesogenic units and crown ether cycles of cis-4,4'-bis(4-hydroxyphenylazo) dibenzo-14-crown-4 was synthesizeed via solution cocondensation polymerizations from 4, 4'-(alpha, omega-octanedioylxy)dibenzoyl dichloride (M-1), 2, 5-bis (p-dodecyloxybenzoyloxy) hydro-quinone (M-2) and cis-4,4'-bis(4-hydroxyphenylazo)dibenzo-14-crown-4 (M-3) as the monomers. Monomer M, was synthesized by esterification and substitution reaction of p-hydroxybenzoic acid and octanedioyl chloride. Monomer M, was synthesized by esterfication and reduction reaction of 2, 5-dihydroxybenzoquinone and p-dodecyloxybenzoyl chloride. Monomer (M-3) was synthesized by diazotization and coupling reaction of cis-diaminodibenzo-14-crown-4 and phenol. The molecular weights of copolyesters are not high, and the [eta] of the copolyesters ranges from 0.35 similar to 0.25 dL/g. The monomer structures were identified by using elementary analysis, IR, UV, H-1-NMR and MS etc. All the copolyester samples are yellowish powders and insoluble at room temperature in THF and CHCl3 except for sample CP9. The properities of copolyesters were investigated by using GPC, [eta], 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 (T-m). The thread texture and schlieren texture can be observed. Their melting temperature and isotropic temperature (T-1) change regularly with varying the cis-4,4'-bis(4-hydroxyphenylazo)dibenzo-14-crown-4 unit content in the copolyesters. The WAXD study illustrated that the copolyesters are liquid crystalline with a nematic phase. A dispersive peak at 2 theta near 20 degrees appeared in their WAXD patterns, which is a typical character for quenched nematic liquid crystal copolyesters.