Abstract
A number of thermotropic liquid crystalline polyurethanes with mesogenic unit were synthesized by polyaddition of a para-type diisocyanate such as 1, 4-phenylene diisocyanate(1,4-PDI) with 4, 4'-bis($\omega$-hydorxyalkoxy) biphenyls($BP{m}$) in DMF. The thermal and liquid crystab line properties were examined by differential scanning calorimetry(DSC), polarized optical microscopy, and wide-angle X-ray scattering(WAXS). Intrinsic viscosities of the polymers exbibited two endothermic peaks correspondinding to phase transitions of melting and isotropization. For example, polyurethane(1,4-PDI/($BP{11}$) ) was found to display a liquid crystalline phase between 177 to 205$^{\circ}C$. In order to know how the hydrogen bonding interaction affects the formation of mesophases in polyurethane 1, 4-PDI/($BP{8}$) / thermal processing FT-IR measurements were carried out. It was found that the stretches regarded as shift to higher frequency region with increasing temperature which showed grdually their liquid crystalline phase