Determination of Rotational Viscosity of Nematic Liquid Crystals   from Transient Current: Numerical Analysis and Experiment

Imai, Masahiro; Naito, Hiroyoshi; Okuda, Masahiro; Sugimura, Akihiko

doi:10.1143/jjap.33.3482

Cited by 22 publications

(12 citation statements)

References 19 publications

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“…The calculated rotational viscosities are 0:08 AE 0:01 and 0:10 AE 0:01 Pa s respectively, and agree within an experimental error due to the cell thickness measurement, the accuracy of which is within $AE5%. Rotational viscosity of this compound was also measured by using a transient current method by Imai et al 21) and was slightly larger (0.14 Pa s) than our results. Finally we present the summary of the obtained quantities, anchoring strength (W), pretilt angle (), and rotational viscosity ( 1 ) in cells coated with CYTOP and AL-1254 in Table I.…”

supporting

confidence: 49%

Perfluoropolymer as Planar Alignment Layer for Liquid Crystal Mixtures

Kumar¹,

Takezoe

Dhara³

2011

Jpn. J. Appl. Phys.

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We report a perfluoropolymer (CYTOP) provides planar alignment to liquid crystal mixtures (e.g., ZLI-2293) that are used in display. We found that the anchoring energy of ZLI-2293 on CYTOP is almost eighteen times less and the pretilt angle is slightly larger than on AL-1254. It is expected that the low surface anchoring and high transmission in CYTOP cell will make CYTOP a suitable aligning agent for LC displays as well as many other LC devices. #

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supporting

confidence: 49%

Perfluoropolymer as Planar Alignment Layer for Liquid Crystal Mixtures

Kumar¹,

Takezoe

Dhara³

2011

Jpn. J. Appl. Phys.

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“…As indicated, the clearing temperature T ni , dielectric anisotropy, and birefringence of the CNT-doped cell were almost the same as pure LC although it was measured only for specific amount of CNTs. However, the rotational viscosity measured by transient current method [18] shows decrease of rotational viscosity to some degree and however, the effect was large in the SWNT-doped cell. Next, we measured electro-optic characteristics of the cells.…”

Section: Resultsmentioning

confidence: 88%

Carbon Nanotube Effects on Electro-Optic Characteristics of Twisted Nematic Liquid Crystal Cells

Srivastava

Bae

et al. 2009

Molecular Crystals and Liquid Crystals

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Twisted nematic (TN) liquid crystal (LC) cells doped with carbon nanotubes (CNTs) were fabricated and their electro-optic characteristics were studied. The CNTs with a minute amount of doping did not disturb the liquid crystal orientation in the off and on state. Effects of CNTs on voltage-dependent transmittance curves and voltage holding ratio were not found to be so strong. The response time however was improved as compared to pure LC.

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“…The transient current method [39,40] was used to obtain γ 1 for the nematic samples and the experimental details are mentioned elsewhere. [30] Figure 7(a) shows that γ 1 of the hybrid is lower than that of the pure LC -which explains the faster electro-optic response for the 5CB + graphene hybrid.…”

Section: Graphene-doped Nematic Lc: Faster Electrooptic Responsementioning

confidence: 99%

Graphene and liquid crystal mediated interactions

2016

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The two-dimensional graphene-honeycomb structure can interact with the liquid crystal's (LC) benzene rings through π-π electron stacking. This LC-graphene interaction gives rise to a number of interesting physical and optical phenomena in the LC. In this paper, we present a combination of a review and original research of the exploration of novel themes of LC ordering at the nanoscale graphene surface and its macroscopic effects on the LC's nematic and smectic phases. We show that monolayer graphene films impose planar alignment on the LC, creating pseudo-nematic domains (PNDs) at the surface of graphene. In a graphenenematic suspension, these PNDs enhance the orientational order parameter, exhibiting a giant enhancement in the dielectric anisotropy of the LC. These anisotropic domains interact with the external electric field, resulting in a non-zero dielectric anisotropy in the isotropic phase as well. We also show that graphene flakes in an LC reduce the free ion concentration in the nematic media by an ion-trapping process. The reduction of mobile ions in the LC is found to have subsequent impacts on the LC's rotational viscosity, allowing the nematic director to respond quicker on switching the electric field on and off. In a ferroelectric LC (smectic-C Ã phase), suspended graphene flakes enhance the spontaneous polarisation by improving the tilted smectic-C Ã ordering resulting from the π-π electron stacking. This effect accelerates the ferroelectric-switching phenomenon. Graphene can possess strain chirality due to a soft shear mode. This surface chirality of graphene can be transmitted into LC molecules exhibiting two types of chiral signatures in the LCs: an electroclinic effect (a polar tilt of the LC director perpendicular to, and linear in, an applied electric field) in the smectic-A phase, and a macroscopic helical twist of the LC director in the nematic phase. Finally, we show that a graphene-based LC cell can be fabricated without using any aligning layers and ITO electrodes. Graphene itself can be used as the electrodes as well as the aligning layers, obtaining an electro-optic effect of the LC inside the cell. P A 50 m P A Planar alignment 0 V 45 V Homeotropic alignment E ARTICLE HISTORY

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Determination of Rotational Viscosity of Nematic Liquid Crystals from Transient Current: Numerical Analysis and Experiment

Cited by 22 publications

References 19 publications

Perfluoropolymer as Planar Alignment Layer for Liquid Crystal Mixtures

Perfluoropolymer as Planar Alignment Layer for Liquid Crystal Mixtures

Carbon Nanotube Effects on Electro-Optic Characteristics of Twisted Nematic Liquid Crystal Cells

Graphene and liquid crystal mediated interactions

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