Synthesis and characterization of segmented copolymers of polystyrene and thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate)

Abstract

A series of segmented copolymers containing a thermotropic liquid crystalline poly(4-oxybenzoate-co-2,6-oxynaphthoate) and an amorphous polystyrene were created and analyzed. The segmented copolymers were prepared by solution polycondensation of α,ω-dicarboxylic acid-terminated polystyrene with 4-hydroxybenzoic acid and 2-hydroxy-6-naphtholic acid in a mixture of triphenylphosphine, hexachloroethane, and pyridine. The obtained polymers were fractionated to isolate the pure segmented copolymers. The segmented copolymers were characterized by FT-IR spectroscopy, differential scanning calorimetry, thermogravimetric analysis, optical polarizing microscopy (OPM), and X-ray diffraction measurement. OPM and X-ray diffraction measurements verified the presence of a nematic liquid crystalline phase for the segmented copolymers. The experimental results indicate that the segmented copolymers have a microphase-separated morphology, that is both amorphous and liquid crystalline properties were shown by the polystyrene and liquid crystalline polyester segments respectively.