Synthesis and characterization of a liquid crystalline polyacetylene with cholesteryl side groups using Schrock-type molybdenum initiators

Abstract

SUMMARY: We report the synthesis and polymerization of a new acetylene monomer with a cholesteryl side group. The monomer shows monotropic behaviour. Polymerization is initiated with the well-defined Schrock-type molybdenum carbene Mo(CHR)(NAr)(OR9) 2 with NAr = 2,6-dimethylaniline, R = C(CH 3 ) 2 C 6 H 5 and R9 = C(CH 3 )(CF 3 ) 2 . Polymerization is almost quantitative and yields a polymer with a comparatively narrow molecular weight distribution. The material is an orange solid which is soluble in common organic solvents at room temperature. The results of DSC, X-ray diffraction, and polarizing optical microscopy (POM) indicate that, upon cooling, the polymer exhibits a mesophase of the smectic A type before undergoing a glass transition.