SYNTHESIS AND PROPERTIES OF LIQUID-CRYSTALLINE POLYACETYLENES WITH A PHENYLCYCLOHEXYL MESOGENIC MOIETY IN THE SIDE-GROUP

We present a series of side-chain liquid-crystalline conjugative polymers, poly(monosubstituted acetylenes), where the side group is composed of a phenylcyclohexyl moiety as a mesogenic core, a methylene chain as a spacer, and an alkyl chain as a terminal group. Monosubstituted acetylene monomers are synthesized and then polymerized by using Ziegler-Natta and metathesis catalysts. Through measurements of DSC (differential scanning calorimetry) and polarizing microscopy, the polymers prepared are found to show a smectic A liquid-crystalline phase with a fan-shaped texture. Characterizations of these polymers are also made in view of molecular weight, thermal isomerization of the cis to trans form, and enthalpy changes associated with phase transitions.