Two series of novel main chain liquid crystalline copolyesters with biphenyl-mesogenic units and azo type crown ether cycles were prepared via solution polycondensation from 4

4′-(α

ω-alkanedioyloxy)dibiphenylyloyl dichloride (M1)

cis－4

4′-bis(4-hydroxy-phenylazo)dibenzo-18-crown-6(M2)

trans 4

4′-bis (4-hydroxy-phenylazo) dibenzo-18-crown-6 (M3) and 1

10-decanediol (M4) as the monomers.The intrinsic viscosity ［η］ of the two series of copolyesters ranges from 0.25～0.35 dL/g and 0.27～0.38 dL/g

respectively.The structures of monomers were identified by elemental analysis

IR

UV-Vis

1HNMR and MS.The properties of copolyesters were investigated by using DSC

TGA

WAXD and POM.All the copolyesters are able to form nematic mesophase after melting.The threaded texture

or ball granul texture or Schlieren texture of nematic phase can be observed on POM.Their melting temperature (Tm) and isotropic temperature (Ti) decrease regularly with increasing the length of flexible spacer in the copolyesters

and the Tm and Ti of copolyesters containing trans crown ether cycles are higher than those of the copolyesters containing cis crown ether cycles.