| Abstract: | A novel series of liquid crystalline copolyesters with T-shaped two-dimensional mesogenic unit and crownether cycle of cis-4,4'-bis(4-hydroxyphenylazo)dibenzo-18-crown-6 was prepared via solution condensation polymerizationfrom 4,4'-(α,ω-hexanedioyloxy)dibenzoyl dichloride (M1), 2-(4'-ethoxyphenyl)hydroquinone (M2) and cis-4,4'-his(4-hydroxyphenylazo)dibenzo-18-crown-6 (M3). The molecular weights of copolyesters are not high, and the intrinsic viscosityη] 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 exceptCP-9. The properties of copolyesters were investigated by using GPC, η], DSC, TG.WAXD and POM. It was found that allthe copolyesters entered into liquid crystalline phase when they were heated to above their melting temperature (Tm). Thethreaded 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 inthe copolyesters. |
