Helix parameters in bi- and multicomponent mixtures composed of orthoconic antiferroelectric liquid crystals with three ring molecular core

Abstract

Eight types of bicomponent systems composed of antiferroelectric compounds with different polarity of achiral chain and different temperature dependence of helical pitch as well as three multicomponent mixtures composed of antiferroelectric compounds with opposite helical twist sense were studied. The phase miscibility was tested by polarising optical microscopy. The results of the helical pitch and helical twist sense measurements obtained by a spectrophotometric method of selectively reflected light and by polarimetric method, respectively, are presented. It was found that it is possible to control helical pitch length and temperature of helix twist inversion in antiferroelectric mixtures by controlling the ratio of compounds with left-and right-handed helix in such mixtures, although all of them have the same chiral terminal chain.

Nanocomposites Based on Antiferroelectric Liquid Crystal (S)-MHPOBC Doping with Au Nanoparticles

“…The temperature dependence of the helix pitch determined for Composites 1-3 is presented in Figure 6. The maximum absorbance along with the uncertainty was appointed based on fitting the Gaussian curve to the experimental data and the helix pitch values p = λ s /2n av in the SmC* and p = λ s /n av in the SmC* A phases were calculated (the average refractive index n av = 1.5 for the SmC* and SmC* A phases) [67,68]. The helix pitch in the SmC* γ phase was calculated as for the antiferroelectric SmC* A phase.…”

The Influence of the Molecular Structure of Compounds on Their Properties and the Occurrence of Chiral Smectic Phases

“…The helical pitch length measurements were performed according to the detailed procedure described in Ref. [22] using a Shimadzu UV-Vis-NIR spectrophotometer (UV-3600, Shimadzu Co., Kyoto, Japan). The spectrophotometer is equipped with a temperature controller, U7 MLW, with a Peltier element.…”

“…The ferroelectric phase (SmC*) was predicted and then discovered by Meyer et al in 1975 [13], and antiferroelectricity in liquid crystals was discovered by Chandani et al in 1989 [14]. Practical applications have only liquid-crystalline mixtures [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] because the composition's tuning allows us to make the optimized ferro-or antiferroelectric mixtures. It is not easy to synthesize compounds with the desired properties.…”

Synthesis, Mesomorphic Properties and Application of (R,S)-1-Methylpentyl 4′-Hydroxybiphenyl-4-carboxylate Derivatives

“…The aim of the work is to discuss the mesomorphic properties of the racemates with a widetemperature anticlinic phase and to demonstrate the advisability of using the racemates as dopants for the antiferroelectric mixtures. If so, it would be possible to extend the range of the antiferroelectric phase and thus increase the helical pitch, which is quite sensitive to doping [3,4,[22][23][24][25]. An analysis of the obtained results is presented.…”