Splay orientation in a capillary (original) (raw)
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Journal of Information Display, 2008
We demonstrated the capillary force lithography (CFL) method for controlling the azimuthal anchoring energy of a liquid crystal (LC) alignment layer. When a thermoplastic polymer film is heated to over the glass transition temperature, the melted polymer is filled into the mold structure by the capillary action and the aspect ratio of the pattern is determined by the dewetting time of the CFL process. Here, the proposed method showed that the azimuthal anchoring energy of the LC alignment layer could be simply controlled by the surface relief patterns which were determined by the dewetting times during the CFL patterning.
Photo-Induced Orientation of Nematic Liquid Crystals in Microcapillaries
Acta Physica Polonica A, 2010
Axial and transversal orientational configurations of a nematic liquid crystal 6CHBT are realized inside glassy cylindrical capillaries by using photoalignment technique. It is demonstrated that this principle can be effectively used to enforce liquid crystal alignment in the desirable direction. It can be applied to control liquid crystal alignment in the photonic crystal fibers showing great potential for the modern telecommunication technologies.
Capillary Flows of Nematic Liquid Crystal
Crystals, 2020
In this paper we report the new experimental results on the rise of a liquid crystal in flat capillaries with inner photosensitive surfaces. The capillaries with different surface orientations were prepared by the use of the photo-alignment technique. Such a surface treatment makes it possible to eliminate the noncontrollable influence of a nanorelief on the wetting process, which takes place in the rubbing treatment technique previously used in similar experiments. The dynamics of the capillary rise of a nematic liquid crystal 5CB (4-cyano-4′-pentylbiphenyl) in vertical plane capillaries with photo-aligned substrates were studied for the first time. It was found that the stationary value of a contact angle weakly depends on the direction of a planar surface orientation relative to the direction of a capillary rise. It has been shown that the application of strong electric fields resulted in a decreasing of the contact angle. The results, obtained for the nematic liquid crystal, are...
Influence of Additives and Surface Topography on the Alignment of Nematic Liquid Crystals
Crystal Research and Technology, 1982
Observations of the influence of a simultaneous action of different surface topographies and polar or nonpolar additives in small concentration on the alignment properties of liquid crystal molecules are reported. The additive dependence of the threshold behaviour of planar aligned liquid crystal cells is also studied.
Alignment and alignment dynamics of nematic liquid crystals on Langmuir-Blodgett mono-layers
Liquid Crystals, 1998
Mono-layers of stearic and behenic acids deposited with the Langmuir-Blodgett technique, were used as aligning films in nematic liquid crystal cells. During the filling process the liquid crystal adopts a deformed quasi-planar alignment with splay-bend deformation and preferred orientation along the filling direction. This state is metastable and transforms with time into homeotropic once the flow has ceased. The transition is accompanied by formation of disclination lines which nucleate at the edges of the cell. The lifetime of the metastable splay-bend state was found to depend on the cell thickness. On heating, anchoring transition from quasi-homeotropic to degenerate tilted alignment in form of circular domains takes place near the transition to the isotropic phase. The anchoring transition is reversible with a small hysteresis.
Alignment Control of a Nematic Liquid Crystal on a Doubly Treated Substrate
Japanese Journal of Applied Physics, 2003
We have investigated the molecular orientation of a nematic liquid crystal (LC) on a doubly treated substrate. One of the substrate surfaces was first treated with the photo-exposure or rubbing process and then subsequently treated with the second photo-exposure process as a function of the irradiation time while the other was prepared with a rubbed polyimide layer for strong anchoring. The LC orientation on the doubly treated substrate was well controlled either by the irradiation time or by the rubbing strength. The observed molecular orientation was consistent with the simulation results based on a torque balance equation. The anchoring energies of the treated substrates were determined from the least-squares fits of the experimental data to the torque balance equation.
Alignment of nematic liquid crystals on mixed Langmuir–Blodgett monolayers
Thin Solid Films, 1998
Mono-layers of stearic and behenic acids and mixtures of them in different proportions, deposited with the Langmuir-Blodgett (LB) technique, were used to study the alignment and the alignment dynamics in nematic liquid crystal cells. A relaxation process from a splay-bend flow induced metastable orientation to the homeotropic one occurs. The lifetime of the metastable state was found to depend on the mono-layer composition. The transition between the homeotropic and the conical anchoring was found to be irreversible in the case of the mixed aligning mono-layers: on cooling from the isotropic phase a quasi-planar nematic state (schlieren texture) appears. It is stable in a range of a few degrees below the clearing point and, on decreasing the temperature, relaxes to the homeotropic state in form of expanding domains.
Liquid crystal alignment in cylindrical microcapillaries
Opto-Electronics Review, 2012
A variety of alignment configurations of liquid crystals (LCs) inside the glassy cylindrical capillaries is realized by using alignment materials providing different anchoring. The radial configuration with central disclination line is obtained for homeotropic boundary conditions. In turn, the axial, transversal and tilted alignment structures are realized by using mate− rials for planar anchoring. The uniformity and controlling of the latter structures were provided by photoalignment method. This approach can be further used to control LC alignment in the photonic crystal fibers recognized as advanced elements for different optical devices.