Pattern-induced anchoring transitions in nematic liquid crystals

  title={Pattern-induced anchoring transitions in nematic liquid crystals},
  author={{\'O}scar A. Rojas-G{\'o}mez and Jos{\'e} M. Romero-Enrique and Nuno Miguel Silvestre and Margarida M. Telo da Gama},
  journal={Journal of Physics: Condensed Matter},
In this paper we revisit the problem of a nematic liquid crystal in contact with patterned substrates. The substrate is modelled as a periodic array of parallel infinite grooves of well-defined cross-section sculpted on a chemically homogeneous substrate which favours local homeotropic anchoring of the nematic. We consider three cases: a sawtooth, a crenellated and a sinusoidal substrate. We analyse this problem within the modified Frank–Oseen formalism. We argue that, for substrate… 
4 Citations

Wetting of Nematic Liquid Crystals on Crenellated Substrates: A Frank–Oseen Approach

We revisit the wetting of nematic liquid crystals in contact with crenellated substrates, studied previously using the Landau–de Gennes formalism. However, due to computational limitations, the

Orientational instability of nematic liquid crystal in a homeotropic cell with boundary conditions controlled by an electric field

ABSTRACT We study the orientational instability of the director in a homeotropic nematic liquid crystal (NLC) cell in a DC electric field. The electric field is applied along or perpendicular to a

Error Estimators and Marking Strategies for Electrically Coupled Liquid Crystal Systems

This paper derives a posteriori error estimators for the nonlinear first-order optimality conditions associated with the electrically and flexoelectrically coupled Frank-Oseen model of liquid



Nematic liquid crystals on sinusoidal channels: the zigzag instability

This work uses the Landau-de Gennes free energy to investigate the texture of nematics in sinusoidal channels with parallel anchoring bounded by nematic-air interfaces that favour perpendicular (hometropic) anchoring and investigates in detail the dependence of the periodicity of the zigzag pattern on the geometrical parameters of the sinusoid channels, which in line with the experimental results is found to be non-linear.

Nematic liquid crystal in contact with periodically patterned surfaces

Nematic liquid crystals confined between two different substrates, possessing alternating stripe patterns of planar and homeotropic anchoring, are studied within the Frank–Oseen theory, in which the

Uniform and nonuniform textures of a nematic liquid crystal in contact with an inhomogeneous substrate.

A second order phase transition is found between the uniform homeotropic or planar alignment and a distorted director configuration and the effect of the stripe width and the anchoring strength on the location of this transition and on the bulk orientation of the nematic director is studied.

Nematic liquid crystal in the wedge and edge geometry in the case of homeotropic alignment

The model based on the Frank-Oseen and Rapini-Papoular formalisms predicts two textures of opposite rotations of the director as in the case of strong anchoring on both surfaces as well as a length scale λ which characterizes the crossover between the regions close to the apex and far from it.

Phase behavior of a nematic liquid crystal in contact with a chemically and geometrically structured substrate.

A zenithally bistable nematic device is investigated by confining a nematic liquid crystal between the patterned grating surface and a flat substrate with strong homeotropic anchoring.

Filling and wetting transitions of nematic liquid crystals on sinusoidal substrates.

It is shown that this double-transition sequence may be strongly modified in the case of ordered fluids, such as nematic liquid crystals, in which the interface remains unbent but bound to the substrate.

Controllable alignment of nematic liquid crystals around microscopic posts: Stabilization of multiple states

Nematic liquid crystal materials are rod-like molecules that align in a locally common direction called the director. This gives rise to anisotropic properties that are used in electro-optical

Wetting transition of a nematic liquid crystal on a periodic wedge-structured substrate

This work generalizes Wenzel's law, which assigns an effective contact angle to a droplet on a rough substrate, when the wetting layer has an ordered phase, like a nematic.

Zigzag line defects and manipulation of colloids in a nematic liquid crystal in microwrinkle grooves

This system, which uses easily fabricated microwrinkle grooves, provides a new microfabrication method based on the arrangement of controllable defects, which demonstrates the importance of boundary conditions and introduced asymmetry for the engineering of topological defects.

Effective free-energy method for nematic liquid crystals in contact with structured substrates.

The effective free-energy method allows one to determine the energy barriers between two states in a bistable nematic device and finds remarkably good agreement between the phase boundaries calculated from the two approaches.