Synthesis and characterization of sulfonated liquid crystalline polyesters

Abstract

Abstract Liquid crystalline polyesters based on hexanediol, dimethyl 4,4′‐biphenyldicarboxylate, and various levels of dimethyl 5‐sodiosulfoisophthalate (0–20 mol%) were prepared using a conventional melt polymerization process. The presence and quantification of the ionic functionality was surveyed using 1 H NMR spectroscopy. Solution viscosities and corresponding molecular weights decreased when the ionic monomer concentration exceeded a critical value (higher than 3 mol%). Differential scanning calorimetry indicated a maximum in the isotropic transition temperature versus ionic modification at approximately 10 mol%. Dynamic mechanical analysis indicated that the glass transition temperature was suppressed due to ionic association at high concentrations (greater than 3 mol%) of ionic functionality. Polarized light microscopy and wide‐angle X‐ray diffraction were used to identify the smectic liquid crystalline and crystalline phases. © 2002 Society of Chemical Industry