On the solution characterization of an all‐aromatic liquid‐crystalline copolyester

Abstract

Solution characterization of the thermotropic liquid–crystalline copolyester synthesized from terephthalic acid, phenyl hydroquinone, and (1‐phenylethyl) hydroquinone (2 : 1 : 1) has been performed. Viscometry, size exclusion chromatography, and light scattering have been carried out under the optimal conditions found for measurement: 85°C in a 50/50 mixture by weight of phenol/1,2,4‐trichlorobenzene. The absolute weight‐average molecular weight from light‐scattering measurements served for calibration of indirect methods of charac‐terization (e.g., the limiting viscosity number [η] is related to the molecular weight by [η] = 5.10 × 10−4 Mw0.72), and the molecular weight per unit chain length, \documentclass{article}\pagestyle{empty}\begin{document}$ \bar M_L * $\end{document}, from light scattering and size exclusion chromatography (SEC) is found to be 28 Å−1, consistent with theoretical expectations. The calculated persistence length q is 28 Å. Moreover, the meth‐odology of SEC characterization enables the kinetics of solid‐state postpolymerization of this liquid‐crystalline copolyester to be studied. © 1993 John Wiley & Sons, Inc.