Structure of liquid crystalline copolyesters from two acetoxybenzoic acids and polyethylene terephthalate

The molecular and supermolecular structures of thermotropic liquid crystalline copolyesters from p-acetoxybenzoic acid (B), polyethylene terephthalate (E), and m-acetoxybenzoic acid (M) were studied by Fourier transform infrared spectrometer, 200-MHz ¹H-nuclear magnetic resonance (NMR), and wide-angle X-ray diffraction methods. The assignments of resonance peaks in NMR spectra are given and the effect of B/E/M molar ratio on the NMR spectra and number-average degree of polymerization of the copolyesters are discussed. The equatorial, meridional, and azimuthal scans, and their dependency on monomer mole ratio for the copolymers, are elaborated. The persistence length and orientation of the copolymer ribbons were found to increase with an increase in p-oxybenzoate unit content from 60 to 75 mol % at a fixed m-oxybenzoate unit content of 5 mol %. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 2921–2925, 1999