Phase Diagrams of Binary Mixtures of Antiferroelectric and Ferroelectric Compounds with Lactate Units in the Mesogenic Core

Abstract

Binary mixtures based on lactic acid derivatives were prepared and studied. Pure compounds differ in the type of linkage of the non-chiral chain to the molecular core, either keto or ether groups, and besides the SmA and SmC* phases they exhibit the antiferroelectric SmC _A * or hexatic SmF(I)* phases, respectively. Phases and phase transition temperatures of mixtures were determined. Spontaneous polarization and tilt angle were evaluated in the SmC*, SmC _A * and/or SmF(I)* phases. Dielectric spectroscopy has yielded behaviour of modes in vicinity of the phase transition to the antiferroelectric or hexatic phase. The phase diagrams of mixtures show the stability of the hexatic and antiferroelectric phases. These phases become narrower and eventually disappear when concentration of both components approaches to the balance.

Keywords:

• Ferroelectric liquid crystals
• binary mixtures
• lactic acid

Acknowledgements

This work was supported by Grants No. 202/02/0840, No. 202/03/P011 from the Grant Agency of the Czech Republic and EU Project COST D-14 WG00015.