Electrically controlled local Frédericksz transition in a layer of a nematic liquid crystal

Sutormin, V. S.; Krakhalev, M. N.; Prishchepa, O. O.; Zyryanov, V. Ya.

doi:10.1134/s0021364012200131

Cited by 20 publications

(26 citation statements)

References 13 publications

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“…For instance, the transition from the homeotropic director configuration into the homeoplanar one caused by the ionic modification of surface anchoring begins at U = 2.7 V for the cell based on MBBA (Δε < 0) doped with CTAB. This value is close to the threshold voltage (Uth = 2.8 V) of 5CB-cell operated by the ionic-surfactant method [16,17]. The reorientation of MBBA can not be explained by the Frederiks effect ( Figure 1(b)) since the threshold field (Equation (2)) would be about 4 V for our cell [21].…”

Section: Resultssupporting

confidence: 72%

“…As a result, the transition from the homeotropic director configuration into the hybrid homeoplanar one occurs within the LC cell ( Figure 2). This orientational transition has been investigated previously in the LC cell based on 5CB (Δε > 0) doped with CTAB [16,17].…”

Section: Resultsmentioning

confidence: 65%

“…We are developing the method of electrically induced modification of surface anchoring of nematics by using ionic surfactants. The ionicsurfactant method was applied previously both to the polymer dispersed liquid crystals [12][13][14][15] and the LC layer cells [16][17][18].…”

Section: Introductionmentioning

confidence: 99%

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Electrically induced anchoring transition in nematics with small or zero dielectric anisotropy

et al. 2016

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Electrically induced anchoring transition in nematics with small or zero dielectric anisotropy The orientational transitions induced by electrically controlled ionic modification of surface anchoring in liquid crystal cells based on the nematics with small or zero dielectric anisotropy Δε are considered. The type of director reorientation is shown to be independent of the sign of dielectric anisotropy and can be the same for the nematics with both negative and positive Δε. Besides, the orientational transition and corresponding switchable optical states do not depend on the Δε value and can be effectively realized even for the nematics with zero dielectric anisotropy.

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Section: Resultssupporting

confidence: 72%

Section: Resultsmentioning

confidence: 65%

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Electrically induced anchoring transition in nematics with small or zero dielectric anisotropy

et al. 2016

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“…The method of electrically controlled modification of the surface anchoring by using the ionic surfactants has been developed for the nematic LC droplets [14][15][16][17], nematic layers [18][19][20] and cholesteric droplets [21]. For the nematic layers, the transitions from the homeotropic structure into the homeoplanar director configuration [18,19] and from the homeoplanar configuration into the twist structure [20] were found and studied.…”

Section: Introductionmentioning

confidence: 99%

“…For the nematic layers, the transitions from the homeotropic structure into the homeoplanar director configuration [18,19] and from the homeoplanar configuration into the twist structure [20] were found and studied.…”

Section: Introductionmentioning

confidence: 99%

Orientational transition in the cholesteric layer induced by electrically controlled ionic modification of the surface anchoring

et al. 2016

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A reorientation of cholesteric liquid crystal with a large helix pitch induced by the electrically controlled ionic modification of the surface anchoring has been studied. In initial state, the cholesteric helix is untwisted completely owing to the normal surface anchoring specified by the cations adsorbed at the substrates. As a result, the homeotropic director configuration is observed within the cell. Under the action of dc electric field, one of the substrates becomes free from the layer of surface active cations, therefore, setting the planar surface anchoring. The latter, in turn, leads to the formation of the hybrid chiral structure. The threshold value and dynamic parameters have been estimated for this process as well as the range of control voltages, which do not allow the electrohydrodynamic instabilities. The twisted hybrid director configuration observed in the experiment has been analyzed by means of the simulation of polarization change of light propagating through the cholesteric layer with asymmetric (planar and homeotropic) surface anchoring on the cell substrates.

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Anionic-cationic surfactant mixture providing the electrically controlled homeotropic surface anchoring of liquid crystals

Krakhalev

Sutormin

Prishchepa

et al. 2019

Journal of Molecular Liquids

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4-heptyloxybenzoate benzyl dodecyldimethylammonium (HOBBDDA) is synthesized and its orienting influence on nematic liquid crystal 4-pentyl-4'-cyanobiphenyl (5CB) is tested. HOBBDDA dissolved up to 1.4 percent in 5CB droplets dispersed in polymer film does not change the tangential surface anchoring inherent to polyvinyl alcohol matrix used. Homeotropic surface anchoring is realized if the HOBBDDA content exceeds 1.7 percent. The molecules of the surfactant in 5CB dissociate into anions and cations. The anions modify the surface anchoring under the action of DC electric field both in the normal and inverse mode. The mixture of HOBBDDA and cetyltrimethylammonium bromide can function as a binary ioniccationic surfactant which significantly expands the prospects for using the ionic-surfactant method to control liquid crystal materials.

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Electrically controlled local Frédericksz transition in a layer of a nematic liquid crystal

Cited by 20 publications

References 13 publications

Electrically induced anchoring transition in nematics with small or zero dielectric anisotropy

Electrically induced anchoring transition in nematics with small or zero dielectric anisotropy

Orientational transition in the cholesteric layer induced by electrically controlled ionic modification of the surface anchoring

Anionic-cationic surfactant mixture providing the electrically controlled homeotropic surface anchoring of liquid crystals

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