Miscibility of blends of thermotropic liquid crystalline polymer and sulfonated polystyrene ionomers

The miscibility of a wholly aromatic thermotropic liquid crystalline polyester (LCP) with lightly sulfonated polystyrene ionomers (SPS) was assessed. Zinc salts of an SPS with 5.3 mol % sulfonation were miscible at all compositions with the LCP, but lithium salts with the same sulfonation level formed two phases, a pure LCP phase and an ionomer-rich mixed phase. Zinc salts of an ionomer with 10.8 mole % sulfonation were miscible with the LCP when the blend was richer in the ionomer, but two-phase blends were obtained for LCP-rich compositions. Miscibility in this system arose from intramolecular repulsive interactions along the ionomer chain.