Influence of the monomer feeding sequence on the structure and properties of thermotropic liquid‐crystalline poly(ester imide)s

A series of poly(ester imide)s mainly derived from N,N ′‐hexane‐1,6‐diylbistrimellitimides, 4,4′‐dihydroxybenzophenone, and p ‐hydroxybenzoic acid were synthesized by a direct polycondensation method in benzenesulfonyl chloride, N,N ′‐dimethylformamide, and pyridine with different monomer feeding sequences. The molecular structures and properties of the resultant poly(ester imide)s were characterized with NMR, IR spectrometry, polarized light microscopy, wide‐angle X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The results showed that the monomer feeding sequences had a great effect on the sequential structure of the molecular chains of the copolymers and consequently on their liquid‐crystalline (LC) properties, fiber‐forming capability, and other properties. Thus, it is probable that one could obtain an LC poly(ester imide) with given properties by controlling the monomer feeding sequence during the polycondensation process. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008