Effect of Extended π-Conjugated on a Ferroelectric Columnar Phase

Abstract

Ferroelectric columnar liquid crystals are materials in which the polar direction can be controlled by applying a voltage and can be maintained after removal of the voltage. In this study, we investigated the effect of replacement of the aromatic sites from phenyl to biphenyl group in urea molecule. Here, isomeric compounds 1 and 2 were prepared for the investigation. Compound 1 exhibited a columnar phase, whereas compound 2 exhibited an isotropic liquid. The 1D and 2D-XRD measurement of compound 1 showed the peaks originated in its helical column structure. Second harmonic generation (SHG) measurements of 1 revealed that its columnar liquid crystal phase has ferroelectric temperature range and the polarization is fixed in its crystal phase.