FT-IR study of phase transition behavior of ferroelectric liquid crystals

Abstract

Ferroelectric liquid crystals(FLCs) with an optically active alkanoyl group and a chiral group derived from lactic acid show very large spontaneous polarization (Ps) of over 1000 nC/cm^2. In order to further analyse the phase transition behavior of these FLCs, we performed IR analysis on a series of them. The FLC having the highest Ps showed an unusual behavior; that is, the IR absorption of the ketonc C=O stretching vibration shifted to a higher wavenumber at the isotropic to SmC^* phase transition, while those of the other FLCs shifted to lower wavenumber. The relationship between the molecular structure and the IR results will be discussed.