Re-Writable Multi-Domain Liquid Crystal Alignment Layers through Laser-Induced Micropatterning

Li, Xin; Lu, Xue Min; Lu, Qianli; Ohlin, C. André

doi:10.1143/jjap.45.l591

Cited by 3 publications

(2 citation statements)

References 24 publications

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“…8,9 Because AFM might be impractical for large area patterning, other methods were developed, such as photolithography, to generate master masks that can be used to imprint specic patterns onto the aligning photo-active polymer lm, 10 while laser induced micro-patterning was used to generate pattern domains onto polyimide (PI) lms. 11 Furthermore, self-assembling systems were used to obtain uniform alignment in rubbing-free processes. 12 In situ methods have also been developed, such as photo-switchable polymer aligning coatings, e.g.…”

Section: Introductionmentioning

confidence: 99%

In situ laser-imprinted surface realignment of a nematic liquid crystal

2015

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We present a new method for the in-plane realignment of nematic liquid crystals in already fully assembled cells with uni-directionally rubbed polyimide as an aligning layer. We use nematic liquid crystals (NLCs) with a relatively high nematic-isotropic transition temperature and we focus the IR laser beam of the laser tweezers selectively onto one or the other of the inner interfaces. The heat generated by the IR absorption locally melts the liquid crystal and creates an isotropic island with well-defined molecular anchoring at the nematic-isotropic interface. By scanning the laser beam along a pre-defined line, the moving isotropic-nematic interface leaves behind a well oriented LC domain, with LC molecules aligned at 45° to the rubbing direction. If we in addition move the sample with respect to this scanning line, we would be able to selectively realign micro-domains of the liquid crystal with respect to the original alignment induced by the PI rubbing. The realignment can be performed independently on each LC-glass interface, thereby producing predefined domains with customized and controllable alignment within an otherwise uniformly aligned cell.

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Section: Introductionmentioning

confidence: 99%

In situ laser-imprinted surface realignment of a nematic liquid crystal

2015

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“…3 If the solid substrate is endowed with some sort of substructure which may be topological or chemical in nature, 4 even more complex perturbations of the local director field are to be expected that may have important repercussions in the realm of nanooptical devices. 5,6 Experimentally, it is nowadays feasible to prepare submicro-textured substrates in a variety of ways 7-9 including microcontact printing 10 or nanorubbing using the tip of an atomic force microscope. 11 In this latter work the authors succeeded in setting up a solid substrate with a checkerboard pattern where the liquid crystal molecules are anchored planar but with orthogonal orientations between neighboring square unit domains.…”

Section: Introductionmentioning

confidence: 99%

Imprinting substrate structures onto a nematic liquid crystal

Greschek

Gubbins

Schoen

2012

The Journal of Chemical Physics

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By means of Monte Carlo simulations in the grand canonical ensemble we study the morphology of the nematic phase of a simple model liquid crystal interacting with an alternating sequence of chemically different stripes. The stripes anchor molecules such that their orientation is either parallel or perpendicular with the substrate plane. The different molecular orientations are realized through anchoring functions that cause an energetic penalty for molecules oriented in an undesired fashion. We consider combinations of monostable and degenerate anchoring fields. The nature of the nematic phase is characterized through both the local nematic order parameter and the associated local director field. We observe states of uniaxial or biaxial symmetry depending on the ratio of stripe widths and the range of fluid-substrate attraction. In some cases the specific substrate pattern causes regions of biaxial symmetry to coexist with a bulk-like regime sufficiently far away from the substrates in which the local director field indicates a (homogeneous) bent state of the nematic liquid crystal.

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Local structural ordering in surface-confined liquid crystals

S̀liwa

Jeżewski

Захаров

2017

The Journal of Chemical Physics

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The effect of the interplay between attractive nonlocal surface interactions and attractive pair long-range intermolecular couplings on molecular structures of liquid crystals confined in thin cells with flat solid surfaces has been studied. Extending the McMillan mean field theory to include finite systems, it has been shown that confining surfaces can induce complex orientational and translational ordering of molecules. Typically, local smectic A, nematic, and isotropic phases have been shown to coexist in certain temperature ranges, provided that confining cells are sufficiently thick, albeit finite. Due to the nonlocality of surface interactions, the spatial arrangement of these local phases can display, in general, an unexpected complexity along the surface normal direction. In particular, molecules located in the vicinity of surfaces can still be organized in smectic layers, even though nematic and/or isotropic order can simultaneously appear in the interior of cells. The resulting surface freezing of smectic layers has been confirmed to occur even for rather weak surface interactions. The surface interactions cannot, however, prevent smectic layers from melting relatively close to system boundaries, even when molecules are still arranged in layers within the central region of the system. The internal interfaces, separating individual liquid-crystal phases, are demonstrated here to form fronts of local finite-size transitions that move across cells under temperature changes. Although the complex molecular ordering in surface confined liquid-crystal systems can essentially be controlled by temperature variations, specific thermal properties of these systems, especially the nature of the local transitions, are argued to be strongly conditioned to the degree of molecular packing.

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Re-Writable Multi-Domain Liquid Crystal Alignment Layers through Laser-Induced Micropatterning

Cited by 3 publications

References 24 publications

In situ laser-imprinted surface realignment of a nematic liquid crystal

In situ laser-imprinted surface realignment of a nematic liquid crystal

Imprinting substrate structures onto a nematic liquid crystal

Local structural ordering in surface-confined liquid crystals

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