A novel series of liquid crystalline copolyesters with T-shaped two-dimensional mesogenic unit and crown ether cycle of cis-4

4′-bis(4-hydroxyphenylazo)dibenzo-18-crown-6 was prepared via solution condensation polymerization from 4

4′-(α

ω-hexanedioyloxy)dibenzoyl dichloride (M1)

2-(4′-ethoxyphenyl)hydroquinone (M2) and cis-4

4′-bis(4-hydroxyphenylazo)dibenzo-18-crown-6 (M3). The molecular weights of copolyesters are not high

and the intrinsic viscosity [η] of copolyesters ranges from 0.29－0.43. The monomers’ structures were identified by elemental analysis

IR

UV

1H-NMR

MS

etc. All the copolyesters are yellowish powders and insoluble in THF and CHCl3 at room temperature except CP-9. The properties of copolyesters were investigated by using GPC

[η]

DSC

TG

WAXD and POM. It was found that all the copolyesters entered into liquid crystalline phase when they were heated to above their melting temperature (Tm). The threaded texture and schlieren texture of nematic phase can be observed on POM. Their Tm and isotropic temperature (Ti) decrease gradually

while thermal stability increase with varying the content of T-shaped two-dimensional mesogenic unit in the copolyesters.