1. Studies on binary mixtures of nematic liquid crystals made of strongly polar molecules with identical cores and antagonistic orientation of permanent dipoles.
- Author
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Sai, Dasari Venkata, Yoon, Tae Hoon, and Dhara, Surajit
- Subjects
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NEMATIC liquid crystals , *POLAR molecules , *BINARY mixtures , *LIQUID mixtures , *LIQUID crystals , *DIPOLE moments , *LIQUID crystal films - Abstract
We report experimental studies on optical (birefringence, Δn), dielectric (Δε) and bend-splay elastic anisotropies (ΔK = K 33 − K 11) of a few mixtures of two nematic liquid crystals, namely CCH-7 and CCN-47, made of highly polar molecules with identical cores and antagonistic orientation of permanent dipoles. In particular, the polar group (-CN) attached to the bicyclohexane core of CCH-7 is oriented along the longitudinal direction whereas, in CCN-47, it is oriented along the transverse direction. We show that apart from the significant contribution to the optical and dielectric anisotropies, the antagonistic orientation of strongly polar groups plays a crucial role in determining the bend-splay elastic anisotropy. The elastic properties are explained based on a model proposed by Priest, considering the effect of intermolecular association and the resulting length-to-width ratio of the molecules. • Binary mixtures of positive and negative dielectric anisotropy liquid crystals. • Antagonistic orientation of dipoles tends to cancels out their effect. • Antiparallel association increases effective length-to-width ratio of the molecules. • Orientation of dipole moments determines the elastic anisotropy of liquid crystals. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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