Thermotropic liquid crystalline polyesters with terphenyl moieties and flexible ‘ether’ spacers in the main chain

Polyesters with the general formula:

(n=1 (TO 5), 3 (TO 11), 9 (TO 29)) were characterized by differential scanning calorimetry, optical microscopy, miscibility tests and X-ray investigations. In polyesters TO 5 and TO 11 a smectic phase type C occurs. X-ray studies of oriented samples have suggested that the smectic C configuration is azimuthally disordered with the layers orientationally ordered. By contrast, above its melting point the polyester TO 29 shows distinct phases of liquid crystal and isotropic liquid. This is probably due to the polydispersity of the low molecular weight fraction of PEO used in preparing this polyester. A structural model is proposed to illustrate how the polyesters under investigation can adopt organizations compatible with all data known so far.