关键词: 共聚醚, 4, 4'－二羟基氧化偶氮苯, 热致性液晶高分子, 条带织构

Abstract: The monomer having mesogenic moieties based on 4,4'-dihydroxyazoxybenzene has been prepared.There is no evidence for liquid-crystal properties in the monomer,Aseries 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/Bmole ratio is 1.Nematic thread and schlieren textures of polymers were observed.Schlieren textures observed usually by POMfor nematic LCPwere 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 POMbetween crossed polarizers, is an optical effect of slight alternating deviations of the molecular chain direction from a fibre axis normal to the bands.

Key words: Copolyethers, 4,4'-Dihydroxyazoxybenzene, Thermotropic liquid crystalline polymer, Banded texture