Structure and Polymorphism of Biaxial Bent–Core Smectic Liquid Crystal

Abstract

The mesomorphic properties of a homologous series of achiral bent-core compounds are studied by polarizing optical microscopy, electro-optics and polarization measurements. Induction of a new orthogonal smectic phases with the increase of alkyl side chain length was observed. One of the compounds exhibits a unique phase transition between four non-tilted smectic phases (SmAP_A–SmAP_AR-SmAP_R-SmA). The uniaxial but antiferroelectric nature of SmAP_AR phase was confirmed by POM, current response, the 2nd harmonic electro-optic response and polarization measurements. The structure of SmAP_AR phase was studied theoretically by Next-Nearest-Neighbor model and was identified as SmAP_α.

Keywords:

• Bent-core molecules
• ferroelectricity
• biaxial liquid crystal
• electro-optic effects
• dielectric relaxation

Acknowledgment

The authors thank the EU Grant No. FP7-216025 BIND and SFI Grant No. RFP 06/RFP/ENE039 for funding this work.