Designing liquid crystal alignment surfaces

Kitson, S. C.; Edwards, E. G.; Geisow, Adrian

doi:10.1063/1.2884266

Cited by 7 publications

(7 citation statements)

References 8 publications

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“…In the references above, director configurations in the vicinity of wells or posts have been modelled separately in the past, and the duality of the two cases was suggested by Kitson et al [6]; however, to our knowledge, a unified study of them and their effect on the bulk alignment has not been presented to date. In this paper comprehensive three-dimensional modeling is used to study the liquid crystal structure induced by surfaces patterned with posts or wells of rounded square cross section and of various sizes and separations.…”

Section: Introductionmentioning

confidence: 99%

“…An alternative approach that has received some interest involves patterning the aligning surfaces with either topographic relief features or flat micron-scale regions imposing different LC orientations, e.g., checkerboard or stripe patterns alternating between horizontal and vertical alignment. Techniques used for patterning the surfaces include AFM inscription [5], photolithography [6], nanoimprinting [7], and micro and nanoprinting of chemical alignment patterns [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

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Liquid crystal alignment induced by micron-scale patterned surfaces

et al. 2014

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Induced bulk orientation of nematic liquid crystal in contact with micron-scale patterned surfaces is investigated using the Landau-de Gennes theory by means of three-dimensional simulations. The effect of the size and spacing of square cross-sectional well and post patterns is investigated and shown to influence the orientation of the liquid crystal bulk, far removed from the surface. Additionally, the effective anchoring strength of the induced alignment is estimated using a modified version of the torque balance method. Both azimuthal and zenithal multistability are shown to exist within unique ranges of feature sizes.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Liquid crystal alignment induced by micron-scale patterned surfaces

et al. 2014

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“…8 Related work has induced bistable local director alignment in liquid crystals, yielding applications for low-energy display technologies. [9][10][11] However, to date such methods have only been applied to thermotropic nematic and smectic liquid crystals.…”

Section: Introductionmentioning

confidence: 99%

Elasticity-dependent self-assembly of micro-templated chromonic liquid crystal films

et al. 2014

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We explore micropatterned director structures of aqueous lyotropic chromonic liquid crystal (LCLC) films created on squarelattice cylindrical-micropost substrates. The structures are manipulated by modulating the LCLC mesophases and their elastic properties via concentration through drying. Nematic LCLC films exhibit preferred bistable alignment along the diagonals of the micropost lattice. Columnar LCLC films, dried from nematics, form two distinct director and defect configurations: a diagonally aligned director pattern with local squares of defects, and an off-diagonal configuration with zig-zag defects. The formation of these states appears to be tied to the relative splay and bend free energy costs of the initial nematic films. The observed nematic and columnar configurations are understood numerically using a Landau-de Gennes free energy model. Among other attributes, the work provide first examples of quasi-2D micropatterning of LC films in the columnar phase and lyotropic LC films in general, and it demonstrates alignment and configuration switching of typically difficult-to-align LCLC films via bulk elastic properties.

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“…A very good LC alignment in the region of the grating structure and almost no alignment outside of the grating region is resolved under crossed polarizers rotated by 0°/90° (top image) and 45°/135° (bottom image) with respect to the grating lines. In-plane alignment of an LC medium between the polymer ribbons is induced by surface undulation on the sidewalls of the ribbons [ 63 , 64 , 65 , 66 , 67 ], which is schematically drawn in Figure 1 a. Grey-coloured walls with the periodic surface relief structure indicate polymer ribbons.…”

Section: Experimental Investigationmentioning

confidence: 99%

Electrically Tuneable Optical Diffraction Gratings Based on a Polymer Scaffold Filled with a Nematic Liquid Crystal

et al. 2021

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We present an experimental and theoretical investigation of the optical diffractive properties of electrically tuneable optical transmission gratings assembled as stacks of periodic slices from a conventional nematic liquid crystal (E7) and a standard photoresist polymer (SU-8). The external electric field causes a twist-type reorientation of the LC molecules toward a perpendicular direction with respect to initial orientation. The associated field-induced modification of the director field is determined numerically and analytically by minimization of the Landau–de Gennes free energy. The optical diffraction properties of the associated periodically modulated structure are calculated numerically on the basis of rigorous coupled-wave analysis (RCWA). A comparison of experimental and theoretical results suggests that polymer slices provoke planar surface anchoring of the LC molecules with the inhomogeneous surface anchoring energy varying in the range 5–20 μJ/m2. The investigated structures provide a versatile approach to fabricating LC-polymer-based electrically tuneable diffractive optical elements (DOEs).

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Designing liquid crystal alignment surfaces

Cited by 7 publications

References 8 publications

Liquid crystal alignment induced by micron-scale patterned surfaces

Liquid crystal alignment induced by micron-scale patterned surfaces

Elasticity-dependent self-assembly of micro-templated chromonic liquid crystal films

Electrically Tuneable Optical Diffraction Gratings Based on a Polymer Scaffold Filled with a Nematic Liquid Crystal

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