Combined type liquid crystalline poly(oxy-1,4-phenyleneoxyterephthaloyl)s bearing cholesterol pendants attached through polymethylene spacers

Abstract

A series of combined type thermotropic liquid crystalline (LC) poly(oxy-1,4-phenyleneoxyterephthaloyl)s bearing pendant cholesterol moieties attached to the backbone through oxyalkyleneoxy groups (hexamethylene, octamethylene, decamethylene, and dodecamethylene) of varying length, hate been synthesized anew. And their LC properties and, especially, the dependence of mesophase morphology on the spacer length were studied by differential scanning calorimetry (DSC), optical microscopy, and small (SAXD)- and wide-angle X-ray diffractometry (WAXD). All the polymers were found to be amorphous, but thermotropic. And they formed layered morphologies in their mesophase when the spacer group is long. According to SAXD analysis the layered structure becomes better defined as the length of spacers increases. They exhibit two thermal transitions before isotropization. The lower temperature occurs between 34 and 56 degreesC, and the high-temperature ones between 94 and 156 degreesC, both of which decrease with increasing the length of the spacers.