Synthesis and characterization of segmented copolymers of aromatic polyether sulfone and thermotropic liquid crystalline poly(oxy-1,4-phenylenecarbonyl-co-oxy-2,6-naphthaloyl)

Abstract

The synthesis of segmented copolymers of aromatic polyether sulfone and thermotropic liquid crystalline poly(oxy-1,4-phenylenecarbonyl-co-oxy-2,6-naphthaloyl) is presented. The segmented copolymers were prepared by solution polycondensation of hydroxy-terminated polyether sulfone with 4-hydroxybenzoic acid and 2-hydroxy-6-naphthoic acid in a mixture of triphenylphosphine, pyridine and hexachloroethane. The obtained polymers were fractionated to isolate the pure segmented copolymers. All of the segmented copolymers reveal two glass transitions. The first glass transition at about 75 degrees C belongs to the segmental motions of liquid crystalline polyester blocks. The second glass transition at about 140 degrees C belongs to the segmental motions of polyether sulfone blocks. Optical polarizing microscopy and X-ray diffraction measurements verify the presence of a nematic liquid crystalline phase for the segment copolymers. The experimental results indicate that the segmental copolymers have a microphase-separated morphology, i.e., both amorphous and liquid crystalline properties are shown by the polyether sulfone and liquid crystalline polyester segments, respectively.