SYNTHESIS AND CHARACTERIZATION OF CERTAIN PHOTOCROSSLINKABLE RANDOMCOPOLYESTERS FROM 4,4′-OXYBIS(BENZOIC ACID)

A series of new thermotropic liquid crystalline random copolyesters with ethereal linkages were prepared from a potential mesogenic 4,4′-oxybis(benzoic acid) by direct polycondensation with different aliphatic and aromatic diols in pyridine solution. Diphenylchlorophosphate (DPCP) was employed as the condensation agent. Viscosity measurements, FT IR, 1H and 13C NMR spectral data were used for investigating their structural features. The thermal phase transitions and thermotropic liquid crystalline (TLC) behaviour of these polymers were investigated by differential scanning calorimetry (DSC) and optical polarizing microscopy (OPM). Scanning electron microscopy (SEM) coupled with UV irradiation experiments were used to establish the photocrosslinkability of these polyesters. Interestingly, these copolyesters containing arylidene keto moiety in the main chain exhibited nematic mesophase and were photocrosslinked upon UV irradiation.