Synthesis, Characterization, and Electro-Optic Properties of Novel Ferroelectric Liquid Crystal with a Large Tilt Angle and Wide Temperature Range of Chiral Smectic C Phase

Abstract

The present article is a study of the ferroelectric behavior in low-molar-mass organosiloxane liquid-crystal materials classed. A few novel compounds with large tilt angle and wide temperature range of the SmC* phase have been synthesized, and the mesophases exhibited by them have been compared. The mesophases under discussion were investigated by means of polarizing microscopy, differential scanning calorimetry, X-ray diffraction, as well as electro-optical experiments. The influence of the molecular structure on the occurrence of the SmC* phase was investigated. Finally, the electro-optical properties of the SmC* phase, such as tilt angle, dielectric permittivity, and switching behavior, were also measured. As a consequence, the correlation between their electro-optical properties and chemical structures of these compounds is investigated.

Keywords:

• Chemical reactions
• optical microscopy
• thermal analysis

Acknowledgment

We thank Dr. Jey-Jau Lee for help with the XRD experiments at National Synchrotron Radiation Research Center (NSRRC, for the beamline BL17A) in Taiwan. Financial support from the National Science Council of Taiwan (ROC) through 98-2221-E-011-004 is gratefully acknowledged.

Notes

^a Abbreviations: Cr = crystalline phase; SmC* = chiral SmC phase; I = isotropic phase (• = phase exists).

^a The data were measured at T_c − T = 20°C.