Synthesis and characterization of liquid crystalline ionomers with polymethylhydrosiloxane main-chain- and side-chain-containing sulfonic acid groups

摘要

A novel thermotropic side-chain liquid crystalline ionomer (LCI) containing sulfonic acid groups on the side-chain was synthesized by graft copolymerization of mesogenic monomer 4-allyloxy-benzoxy-4'-methoxyphenyl (ABM) and nonemesogenic monomer 4-allyloxy-azobenzene sulfonic acid (AABS) upon polymethylhydrosiloxane (PMHS). The chemical structures of the polymers were confirmed by IR spectroscopy. DSC and TGA were used to measure the thermal properties of those polymers and the mesogenic properties were characterized by polarized optical micrography (POM), DSC, and WAXD. The clearing point temperature (T-c) of these liquid crystalline ionomers was enhanced 50-60 degrees C compared with the polymer without ionic groups. The LCIs exhibit a broad smectic mesogenic region of 80-90 degrees C; the thermal stability below 200 degrees C of the polymers decreases with increasing sulfonic acid concentration. The inherent viscosity of 0.5% solutions decreased with increasing sulfonic acid concentration in the polymer chains. (C) 1998 John Wiley & Sons, Inc. [References: 4]