Synthesis and characterization of liquid crystalline copolymers containing poly (ether sulfone) segments

A new block copolymers (BCP) containing poly (ether sulfone) (PES) with different chain lengths and thermotropic liquid crystalline polyester (TLCP) segments were synthesized by high temperature solution polymerization of the constituent monomers of TLCP and PES oligomers terminated with a hydroxyl group. The chemical structure and inherent viscosity of BCP were characterized by Fourier transform infrared spectroscopy, Ubbelohde viscometer and solubility test, respectively. The thermal behavior, liquid crystallinity, texure and thermal stability of liquid crystalline block copolymer were investigated by a variety of experimental techniques including differential scanning calorimetry, polarizing light microscopy and thermogravimetric analysis. BCP showed a single glass transition temperature and melting point but blends of corresponding homopolymers were biphasic. It showed the typical nematic texture above its T-m depending on the composition and good thermal stability. Such block copolymers can be used as compatibilizer or melt viscosity modifying agent for the blends due to their chemical structure similar to the blend partners, respectively.