Polarization of three-ring Schiff base ferroelectric liquid crystals

ABSTRACT

Chiral smectic C* (SmC*) phase possessing high spontaneous polarization has been of huge interest due to its academic as well as technological importance. Herein, we report the results of temperature and field variation polarization measurements performed on five structurally analogous calamitic three-ring ferroelectric liquid crystals (FLC) belonging to a homologous series, showing the SmC* phase. Of the five FLCs studied, three are (R)-enantiomers referred to as SB(R)-9, SB(R)-11, SB(R)-12 and the other two are (S)-enantiomers denoted as SB(S)-10 and SB(S)-11. These newly synthesised FLCs exhibit blue phase-I/II (BPI or BPII), chiral nematic (N*) phases and a metastable smectic (SmX) phase occurring below the SmC* phase. The polarization in the SmC* phase increases with the increase in the voltage due to the unwinding of the helix and gets saturated when the helix is completely unwound at a higher voltage. The polarization appears at N*-SmC* transition point and increases with a decrease in the temperature in the ferroelectric SmC* phase. The results obtained have been described based on the intermolecular interaction as well as a dipolar contribution, and these results may facilitate to understand the structural-property relationship of FLCs.

Graphical Abstract

KEYWORDS:

• Liquid crystals
• phase transitions
• smectic C* phase
• spontaneous polarisation
• switching

Acknowledgements

Authors gratefully acknowledge the technical help rendered by Mr Rahul Uttam, Centre of Material Sciences, University of Allahabad, Prayagraj.

Disclosure statement

No potential conflict of interest was reported by the author(s).