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 polym ers, poly(monosubstituted acetylenes), where the side group is compose d of a phenylcyclohexyl moiety as a mesogenic core, a methylene chain as a spacer, and an alkyl chain as a terminal group. Monosubstituted a cetylene monomers are synthesized and then polymerized by using Ziegle r-Natta and metathesis catalysts. Through measurements of DSC (differe ntial scanning calorimetry) and polarizing microscopy, the polymers pr epared are found to show a smectic A liquid-crystalline phase with a f an-shaped texture. Characterizations of these polymers are also made i n view of molecular weight, thermal isomerization of the cis to trans form, and enthalpy changes associated with phase transitions.