Surface reorientation dynamics of nematic liquid crystals

Faetti, Sandro; Nobili, Maurizio; Raggi, I.

doi:10.1007/s100510050955

Cited by 55 publications

(61 citation statements)

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“…This effect is caused by adsorption-desorption of LC molecules from/to the aligning layer with a weak anchoring energy and in the presence of the twist elastic torque. [16][17][18] If our assumption about different structures of the chalcogenide surface for the cases of the irradiation from the different sides is correct, the difference in the relaxation times can be explained by different director viscosities on the surface with the different structures.…”

Section: Discussionmentioning

confidence: 96%

Photoalignment in the isotropic phase of liquid crystal on chalcogenide glass film

et al. 2014

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We discovered the phenomenon of liquid crystal (LC) alignment on a photosensitive chalcogenide glass film As 20 Se 80 after irradiation of the LC in the isotropic phase with polarised light. The photoalignment was observed after cooling of the LC to the nematic phase. Quality of the photoalignment depended on an initial phase state of the LC. If the photoalignment was uniform at the irradiation of the isotropic phase of the LC that initially was pre-aligned in the nematic phase, the irradiation of the cell being filled in the isotropic phase resulted in inhomogeneous photoalignment. The orientation of the LC strongly depended on the geometry of the irradiation the LC in the cell. In the case of the direct irradiation of the chalcogenide surface, the photoorientation of the LC was stable. On the contrary, the irradiation of the chalcogenide surface through the LC layer led to the temporal photoalignment that diminished within few days. The results are explained in the frame of the model that suggests two mechanisms of photoalignment. The first one is related to a light-induced anisotropy on chalcogenide layer and the second one involves a LC in the process. We assume that an anisotropic light-induced desorption of LC molecules from the chalcogenide layer is the origin of last kind of photoalignment. The asymmetry of the photoalignment properties at the irradiation from the different sides of the chalcogenide surface is explained by producing different surface structures at the irradiation from the different sides.

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Section: Discussionmentioning

confidence: 96%

Photoalignment in the isotropic phase of liquid crystal on chalcogenide glass film

et al. 2014

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“…In recent years, several analyses have focused on the role played by the surface viscosity in the dynamical behaviour of nematic liquid crystal (NLC) cells [1][2][3][4][5][6]. This significant attention of the scientific community is due in part to the importance of the problem in display technology and, to a considerable extent, in view of the important mathematical issues it raises [7][8][9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

Surface viscosity and reorientation process in an asymmetric nematic cell

2010

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2010) Surface viscosity and reorientation process in an asymmetric nematic cell, Liquid Crystals, 37:12, 1559-1568,The influence of surface viscosity and anchoring energy on the reorientation process of a nematic liquid crystal cell is theoretically investigated. The cell is a slab of thickness, d, whose limiting surfaces are characterised by different anchoring strengths and present easy directions parallel to the bounding surfaces, changing with time due to some external action. The exact space-time profile of the director angle is obtained by means of integral transform techniques and a Green function approach. From this formalism, the time dependence of the optical path difference is exactly determined and its behaviour is analysed in connection with the presence of surface viscosity and different anchoring energies. The problem is also exactly solved in the presence of a constant electric field. It is shown that the compatibility problem between the time derivative of the director field on the surface and in the bulk can be avoided.

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“…7 and 8 and the difference is just in the physical meaning of these equations and values of microscopic parameters. The situation gets even more complicated since a drift of the easy axis can be observed both on rigid inorganic surfaces [4] with no flexible surface fragments and on soft polymer surfaces. One can suggest that the only adsorption/desorption mechanism governs the drift of the easy axis on the rigid surface and both mechanisms contribute to the gliding effect on a soft polymer surface.…”

Section: Introductionmentioning

confidence: 99%

Formation and dynamics of easy orientation axis in magnetic field on PVCN-F surface

Buluy

Reznikov

Slyusarenko

et al. 2006

Opto-Electronics Review

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We describe the experiments on a magnetically-induced drift of the easy axis on a soft surface of photoaligning material fluoro-polyvinyl-cinnamate. We found unexpected partial relaxation of the drift of the easy axis after switching the magnetic field off. This relaxation cannot be explained in a framework of the existing models and requires additional assumptions about the drift process. We propose a model that explains the experimental data suggesting elastic-like behaviour of the polymer fragments during the drift of the easy axis.

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Surface reorientation dynamics of nematic liquid crystals

Cited by 55 publications

References 1 publication

Photoalignment in the isotropic phase of liquid crystal on chalcogenide glass film

Photoalignment in the isotropic phase of liquid crystal on chalcogenide glass film

Surface viscosity and reorientation process in an asymmetric nematic cell

Formation and dynamics of easy orientation axis in magnetic field on PVCN-F surface

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