Visual evaluation of surface anchoring strength by electrohydrodynamic convection of a nematic liquid crystal

2017 ◽  
Vol 96 (4) ◽  
Author(s):  
Gyu Jin Choi ◽  
Jae Min Song ◽  
Chul Gyu Jhun ◽  
Jong-Hoon Huh ◽  
Jin Seog Gwag
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Visual Evaluation ◽  
Surface Anchoring ◽  
Anchoring Strength ◽  
Surface Anchoring Strength

scholarly journals Surface anchoring controls orientation of a microswimmer in nematic liquid crystal

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Hai Chi ◽  
Mykhailo Potomkin ◽  
Lei Zhang ◽  
Leonid Berlyand ◽  
Igor S. Aranson
Keyword(s):  
Liquid Crystal ◽  
Critical Case ◽  
Topological Defects ◽  
Water Soluble ◽  
Critical Surface ◽  
Bacteria Transport ◽  
Surface Anchoring ◽  
Swimming Direction ◽  
Anchoring Strength ◽  
Surface Anchoring Strength

Abstract Microscopic swimmers, both living and synthetic, often dwell in anisotropic viscoelastic environments. The most representative realization of such an environment is water-soluble liquid crystals. Here, we study how the local orientation order of liquid crystal affects the motion of a prototypical elliptical microswimmer. In the framework of well-validated Beris-Edwards model, we show that the microswimmer’s shape and its surface anchoring strength affect the swimming direction and can lead to reorientation transition. Furthermore, there exists a critical surface anchoring strength for non-spherical bacteria-like microswimmers, such that swimming occurs perpendicular in a sub-critical case and parallel in super-critical case. Finally, we demonstrate that for large propulsion speeds active microswimmers generate topological defects in the bulk of the liquid crystal. We show that the location of these defects elucidates how a microswimmer chooses its swimming direction. Our results can guide experimental works on control of bacteria transport in complex anisotropic environments.

Enhanced contrast ratio of homogeneously aligned liquid crystal displays by controlling the surface-anchoring strength

2011 ◽  
Vol 44 (32) ◽  
pp. 325403 ◽  
Author(s):  
Young Jin Lim ◽  
Chang Woo Woo ◽  
Sang Hoon Oh ◽  
Amrita Mukherjee ◽  
Seung Hee Lee ◽  
...  
Keyword(s):  
Liquid Crystal ◽  
Contrast Ratio ◽  
Liquid Crystal Displays ◽  
Surface Anchoring ◽  
Anchoring Strength ◽  
Surface Anchoring Strength

Structure-performance relation of liquid crystal photoalignment with in-situ formation of protection layers

MRS Advances ◽  
2016 ◽  
Vol 1 (52) ◽  
pp. 3517-3523 ◽  
Author(s):  
Kai-Han Chang ◽  
Liang-Chy Chien
Keyword(s):  
Molecular Structure ◽  
Liquid Crystal ◽  
Rigid Core ◽  
Alignment Layer ◽  
Surface Anchoring ◽  
Protection Layer ◽  
In Situ Formation ◽  
Anchoring Strength ◽  
Surface Anchoring Strength

ABSTRACTWe demonstrate a stabilized liquid crystal photoalignment using a surface-localized polymer method. A protection layer is developed on a photoalignment layer (PAL) through phase separation of a mixture composed of reactive monomers (RMs) and liquid crystals (LCs). The RM is polymerized on the PAL which enhances its stability against heat and light with short wavelength. The effects of the concentration and molecular structure of RMs on the electro-optical response and surface anchoring of photoaligned LC device are studied. The concentration of RMs affects the effective cell gap of the LC device. The rigid core length of the RM structure modulates the surface anchoring strength of the alignment layer. Both effective cell gap and surface anchoring strength are key elements for the enhanced dynamic response of LC devices.

Temperature influence on homogeneous instabilities in stationary shear flow of nematic liquid crystal with weak surface anchoring

2010 ◽  
Vol 7 ◽  
pp. 191-201
Author(s):  
I.Sh. Nasibullayev ◽  
O.V. Urina
Keyword(s):  
Liquid Crystal ◽  
Shear Flow ◽  
Nematic Liquid Crystal ◽  
Effect Of Temperature ◽  
External Fields ◽  
Temperature Influence ◽  
Surface Anchoring ◽  
Weak Surface ◽  
Surface Coupling

Plane stationary shear flow of the nematic liquid crystal with weak surface anchoring is investigated. The effect of temperature, external fields, and the nature of the surface coupling on the formation of orientation instabilities is investigated.

Temperature influence on orientation dynamics of oscillatory Poiseuille flow of nematic liquid crystal

2010 ◽  
Vol 7 ◽  
pp. 172-181
Author(s):  
I.Sh. Nasibullayev ◽  
U.R. Kamaletdinova
Keyword(s):  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Poiseuille Flow ◽  
External Influence ◽  
Temperature Influence ◽  
Surface Anchoring ◽  
Orientation Behaviour ◽  
Orientation Change ◽  
Low Amplitude ◽  
Flow Plane

In this work is studying temperature influence and surface anchoring in orientation behaviour of oscillatory Poiseuille flow of nematic liquid crystal (NLC) in the plane cell. Without external influence molecules lays along flow plane. Molecules orientation change and caused by this back-flow is studied by low-amplitude decomposition.

scholarly journals Azimuthal Anchoring Strength in Photopatterned Alignment of a Nematic

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 675
Author(s):  
H. Nilanthi Padmini ◽  
Mojtaba Rajabi ◽  
Sergij V. Shiyanovskii ◽  
Oleg D. Lavrentovich
Keyword(s):  
Liquid Crystal ◽  
Point Defects ◽  
Elastic Energy ◽  
Separation Distance ◽  
Thin Layers ◽  
Uv Exposure ◽  
Surface Anchoring ◽  
Anchoring Strength ◽  
Spatially Varying

Spatially-varying director fields have become an important part of research and development in liquid crystals. Characterization of the anchoring strength associated with a spatially-varying director is difficult, since the methods developed for a uniform alignment are seldom applicable. Here we characterize the strength of azimuthal surface anchoring produced by the photoalignment technique based on plasmonic metamsaks. The measurements used photopatterned arrays of topological point defects of strength +1 and −1 in thin layers of a nematic liquid crystal. The integer-strength defects split into pairs of half-integer defects with lower elastic energy. The separation distance between the split pair is limited by the azimuthal surface anchoring, which allows one to determine the strength of the latter. The strength of the azimuthal anchoring is proportional to the UV exposure time during the photoalignment of the azobenzene layer.

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