Influence of alkoxy chain length and fluorosubstitution on mesogenic and spectral properties of high tilted antiferroelectric esters

Abstract

The synthesis and properties of a few dozen highly evolved analogues of (S)-MHPOBC are reported. The liquid crystal phases, and phase transition temperatures and enthalpies, as evidenced by polarized optical microscopy and differential scanning calorimetry, respectively, are given. The helical pitch in pure compounds and some mixtures is estimated using the selective reflection method. All of the compounds show antiferroelectric phases, and some key structure-property relationships for the new materials are reported. Specifically, it is found that the length of the oligomethylene segment of a novel partially fluorinated alkoxy ether tail incorporated into the structures strongly influences the stability of the antiferroelectric phase and the observed phase sequences, as well as the values of the helical pitch and its temperature dependence. The formulation of a family of broad temperature range eutectic mixtures possessing the highly desirable orthoconic antiferroelectric phases with long helical pitch is described.

Influence of a helical pitch on orthoconic antiferroelectric liquid crystals performance

“…1). This unusual reverse temperature dependence of a pitch enables to prepare antiferroelectric orthoconic mixtures having high pitch in a broad temperature range [12,13].…”

Design, synthesis and mesomorphic properties of chiral benzoates and fluorobenzoates with direct SmCA*-Iso phase transition

“…Moreover, we do not have any information about application ability. We found two types of compounds in our laboratory with direct transition SmC A *-Iso, which show good and interesting properties, [11,12] but they still do not allow to formulate an eutectic multicomponent mixture necessary for applications.…”

“…[11,13] Different structures, also those containing an alkanoyloxyalkoxy terminal chain with fluorinated unit C n F 2n+1 COO-were received and reviewed earlier. [14] Recently, the high tilted antiferroelectric phase was found in compounds with a partially fluorinated alkoxyalkoxy chain.…”

The influence of antiferroelectric compounds on helical pitch of orthoconic W-1000 mixture

“…The synthesis of compounds used for formulation of mixture W-1000 and used as dopants (A-F) has been described in Refs [11,12]. The phase transition temperatures, helical pitch and helical twist sense of mixture W-1000 doped with compounds A-F were measured.…”