Structure of thermotropic copolymers from p-acetoxybenzoic acid, poly(ethylene terephthalate) and six third monomers

Abstract

The molecular and supermolecular structures of thermotropic liquid crystalline copolymers from p-acetoxybenzoic acid, poly(ethylene terephthalate) and third monomers, such as p-acetoxyvanillic acid, p-acetamidobenzoic acid, m-acetoxybenzoic acid, 1,4-diacetoxybenzene/terephthalic acid, 1,5-diacetoxy naphthalene/terephthalic acid, and 2,7-diacetoxynaphthalene/terephthalic acid, were investigated by proton nuclear magnetic resonance (NMR) and wide-angle X-ray diffraction techniques. The assignments of resonance peaks in 1H-NMR spectra are discussed in detail. The characteristics of the NMR spectra for the copolymers with different monomer ratios and different third monomers are illustrated. The number-average degree of polymerization is evaluated by end-group analysis on the basis of NMR spectra. The equatorial and meridional diffractograms of two series of copolymers containing 1,5-naphthylene and 2,7-naphthylene terephthalate as the third monomer units are elaborated.