Rod-shaped dopants for flexoelectric nematic mixtures

Abstract

We report the synthesis and liquid crystalline behaviour of two series of para-substituted terphenyls as dopants with a rigid rod-like shape, rather than a wedge-, pear-or banana-shape, for guest-host nematic mixtures with flexoelectric properties. One series of liquid crystalline dopants is of low-to-strongly negative dielectric anisotropy and the other is of low-to-strongly positive dielectric anisotropy. The usefulness of apolar and polar rod-like dopants as components of flexoelectric nematic mixtures of positive dielectric anisotropy for use in LCDs is investigated in general and the dependence of the flexoelectric properties of the doped nematic mixtures on the polarity of the dopants is studied in particular. The correlation between the concentration of the dopant and the magnitude of the flexoelastic ratio of several guest-host nematic mixtures is investigated.

Terminal end‐group efficiency for the nematic phase using model bicyclo[2.2.2]octanes

“…The data collated in table 6 allow a comparison of the 1-pentyl-4-(3,4,5-trifluorobiphenyl-49-yl)bicyclo[2.2.2]-octane (9, X 1-3 5F) with the 49-pentyl-3,4,5-trifluoroterphenyl (10) [39] and the 1-(4-[trans-4-pentylcyclohexyl]phenyl)-3,4,5-trifluorobenzene (11) [5] differing only in the presence of a 1,4-disubstituted phenyl, cyclohexyl and bicyclo[2.2.2]octyl rings. The terphenyl 10 showed the highest melting point and clearing point.…”

High Birefringence Liquid Crystals

“…4′′-Alkyl-4-cyanoterphenyls were synthesized for the first time in G. Gray's laboratory at the beginning of 1970s [73,74] and their syntheses have been improved up until now because they are important components of many commercial mixtures such as E7 or BL037 and BL038. They are also interesting for their flexoelastic property [104]. Monofluorinated isothiocyanatoterphenyl 28 still exhibits a very high melting point and the smectic phase exists up until 195 °C.…”

From the discovery of the partially bilayer smectic A phase to blue phases in polar liquid crystals

“…The same is observed for some three-ring fluorinated CN compounds. [67] One can see that the compounds with a lower electric permittivity (i.e. comprising a cycloalkane ring) start to develop the SmA d phase at a point in homologous series having terminal chains shorter than those with a higher electric permittivity (i.e.…”