Dipole-induced chiral smectic-C phase in a eutectic mixture of cholesterol esters

Abstract

Both cholesteryl oleate (CO) and cholesteryl oleyl carbonate (COC) are thermotropic mesogens with a general cooling phase sequence: isotropic cholesteric -> smectic crystal. They are almost identical with respect to molecular structure and the central location of molecular dipole. However, the orientation of the latter is axial for CO and transverse for COC. A eutectic mixture of these components shows a phase sequence like the above but involving an induced smectic-C* phase. We explain this discovery on the basis of computer simulation results involving rigid core-dipole-flexible tail model of a mesogen and argue in favor of a ferroelectric liquid crystal model of the induced phase.