Memory effect in filled nematic liquid crystals

Glushchenko, Anatoliy; Kresse, H.; Reshetnyak, Viktor Y; Reznikov, Yuriy; Yaroshchuk, O.

doi:10.1080/026782997208505

Cited by 106 publications

(58 citation statements)

References 12 publications

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“…Md, 82.70.Dd, Colloids in which the solute is liquid crystalline (LC) are known to possess an extremely rich set of behaviors [1,2,3,4,5]. The anchoring between the LC and microcolloidal particles ( 1µm) can produce long-range orientational distortions around the particles.…”

Section: Introductionmentioning

confidence: 99%

“…In such systems aggregated particles produce director distortions extending over macroscopic scales. These suspensions scatter light strongly, and possess unique structural, mechanical, electro-and magneto-optical properties [5,6].Recently, we have shown that even at low concentrations (c part 1%), LC colloids differ strongly from the pure host material [7,8,9,10]. These colloids consist of submicron ferroelectric particles suspended in the LC host.…”

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Orientational Coupling Amplification in Ferroelectric Nematic Colloids

et al. 2006

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We investigated the physical properties of low concentration ferroelectric nematic colloids, using calorimetry, optical methods, infrared spectroscopy and capacitance studies. The resulting colloids normally remain homogeneous, but the nematic orientational coupling is significantly amplified. In particular cases, the nematic orientation coupling increases by 10% for particle concentrations of 0.2%. A manifestation of the increased orientational order is that the clearing temperature of a nematic colloid increases up to 40 Celsius degrees compared to the pure LC host. A theoretical model is proposed in which the ferroelectric particles induce local dipoles whose effective interaction is proportional to the square of the orientational order parameter.PACS numbers: 64.70. Md, 82.70.Dd, Colloids in which the solute is liquid crystalline (LC) are known to possess an extremely rich set of behaviors [1,2,3,4,5]. The anchoring between the LC and microcolloidal particles ( 1µm) can produce long-range orientational distortions around the particles. This results in strong inter-particle interactions -sometimes repulsive and sometimes attractive -in the mesophase. The interactions can give rise to well-ordered structures of particles in the liquid crystal matrix (both lattices and chains) [2,3]. However, in most cases a prerequisite for interesting LC colloidal behavior has been a high concentration dispersion, typically with particle volume fraction c part 30%. In such systems aggregated particles produce director distortions extending over macroscopic scales. These suspensions scatter light strongly, and possess unique structural, mechanical, electro-and magneto-optical properties [5,6].Recently, we have shown that even at low concentrations (c part 1%), LC colloids differ strongly from the pure host material [7,8,9,10]. These colloids consist of submicron ferroelectric particles suspended in the LC host. In these systems, unlike in classic LC colloids, the suspensionmatrix interaction is insufficient to disturb the LC orientation. This small concentration dramatically increases the dielectric anisotropy, significantly decreases the Freedericksz transition voltage, and significantly accelerates electric field-induced director reorientation.In this letter, we report results which show that these phenomena are general properties of liquid crystal suspensions containing ferroelectric colloidal nanoparticles. The addition of impurities normally decreases the nematic clearing temperature T N I [11]. However, our measurements show massive increases in T N I , of the order of 40 • C, for mass impurity concentrations of the order of 0.2%. These results imply an increase in the effective nematic interaction parameter. Measurements of the birefringence, dielectric anisotropy and order parameter in the suspension are consistent with this picture.We have also constructed a theoretical model. The ferroelectric particles in the suspension produce large electric fields in their neighborhood. These electric fields produce induce...

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Orientational Coupling Amplification in Ferroelectric Nematic Colloids

et al. 2006

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“…The memory effect can be utilized for large area outdoor displays with high power consumption, which can significantly be reduced by utilizing the memory effect of PDLC with the field off. For spherical aerosol particles, it has been found that essential contribution to the memory effect is achieved due to formation of ordered branched network of the aerosol particles in the liquid crystal matrix [12]. The present work reports the memory effect of modified clay in PDLC, where modification was made with two different organic surfactants, viz.…”

Section: Introductionmentioning

confidence: 98%

Memory effect of polymer dispersed liquid crystal by hybridization with nanoclay

Jeong¹,

Sun²,

Kang³

et al. 2010

Express Polym. Lett.

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Abstract. The electro-optical performances of polymer dispersed liquid crystal (PDLC) were investigated in the presence of organically modified clays. With the addition and increasing amount of modified clay, driving voltage and memory effect, viz. transparent state of the film after the electricity is off simultaneously increased due most likely to the increased viscosity. Among the two types of modifier, 4-(4-aminophenyl) benzonitrile having greater chemical affinity with LC than hexylamine, gave finer dispersion of clay in liquid crystal, greater viscosity, larger driving voltage and response time, and greater memory effect.

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“…Возникающие цепи и пузыри использовались для визуализации поля директора жидкого кристалла вблизи его поверхности [15,16]. Бистабильный жидкокрис-таллический дисплей, основанный на скоплении диспергированных шаровидных частиц кремне-зема в нематической матрице, был предложен несколькими группами [17][18][19]. Пулен, Рагунатан и др.…”

Section: Introductionunclassified

Physico-Chemical Investigation of Composites Based on Nematic Liquid Crystals

Bayramov¹

2017

Liq. Cryst. and their Appl.

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Memory effect in filled nematic liquid crystals

Cited by 106 publications

References 12 publications

Orientational Coupling Amplification in Ferroelectric Nematic Colloids

Orientational Coupling Amplification in Ferroelectric Nematic Colloids

Memory effect of polymer dispersed liquid crystal by hybridization with nanoclay

Physico-Chemical Investigation of Composites Based on Nematic Liquid Crystals

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