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

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 synthesi zed anew. And their LC properties and, especially, the dependence of mesoph ase morphology on the spacer length were studied by differential scanning c alorimetry (DSC), optical microscopy, and small (SAXD)- and wide-angle X-ra y diffractometry (WAXD). All the polymers were found to be amorphous, but t hermotropic. And they formed layered morphologies in their mesophase when t he spacer group is long. According to SAXD analysis the layered structure b ecomes better defined as the length of spacers increases. They exhibit two thermal transitions before isotropization. The lower temperature occurs bet ween 34 and 56 degreesC, and the high-temperature ones between 94 and 156 d egreesC, both of which decrease with increasing the length of the spacers.