High-quality alignment of nematic liquid crystals using periodic nanostructures created by nonlinear laser lithography

Pavlov I. , Rybak A. S. , Dobrovolskiy A. M. , Kadan V. M. , Blonskiy I. V. , Kazantseva Z. I. , ...More

JOURNAL OF MOLECULAR LIQUIDS, vol.267, pp.212-221, 2018 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 267
  • Publication Date: 2018
  • Doi Number: 10.1016/j.molliq.2018.02.058
  • Page Numbers: pp.212-221


It is well known that today two main and well studied methods for alignment of liquid crystals has been used, namely: rubbing and photoalignment technologies, that lead to the change of anisotropic properties of aligning layers and long-range interaction of the liquid crystal molecules in a mesophase. In this manuscript, we use the nonlinear laser lithography technique, which was recently presented as a fast, relatively low-cost method for a large area micro and nanogrooves fabrication based on laser-induced periodic surface structuring, as a new perspective method of the alignment of nematic liquid crystals. 920 nm periodic grooves were formed on a Ti layer processed by means of the nonlinear laser lithography and studied as an aligning layer. Aligning properties of the periodic structures of Ti layers were examined by using a combined twist LC cell. In addition, the layer of the nanostructured Ti was coated with an oxidianiline-polyimide film with annealing of the polymer film followed without any further processing. The dependence of the twist angle of LC cells on a scanning speed and power of laser beam during processing of the Ti layer was studied. The azimuthal anchoring energy of Ti layers with a periodic nanostructure was calculated. The maximum azimuthal anchoring energy for the nanostructured Ti layer was about 4.6 x 10(-5) J/m(2), which is comparable to the photoalignment technology. It was found that after the deposition of a polyimide film on the periodic nanostructured Ti layer, the gain effect of the azimuthal anchoring energy to -1 x 10(-4) J/m(2) is observed. Also, AFM study of aligning surfaces was carried out. (C) 2018 Elsevier B.V. All rights reserved.