Anatoliy V. Glushchenko

Transformation of hydrogen bonding of a liquid crystal-aerosil system under the influence of an electric field☆

Abstract The transformation of hydrogen bonds in the liquid crystal (5CB)-aerosil system under the influence of an electric field is investigated with the use of IR spectroscopy methods. It is shown that aerosil addition (10 wt.%) to 5CB leads to the formation of weak hydrogen bonds between the aerosil hydroxyl groups and the π-electrons of benzene rings of 5CB (SiOH ⋯ π). Under the influence of an electric field ( U = 60 V, ƒ = 2 kHz ) these bonds undergo a rearrangement, the 5CB molecules in the aerosil pores aligning along the direction of the electric field and thereby forming a new network of hydrogen bonds.

Influence of the Aerosil Surface Modification on Electro-Optical Characteristics of Filled Liquid Crystals

Abstract We have studied the influence of surface state of aerosil on electro-optical characteristics of suspensions ‘aerosil-liquid crystal (LC)’. Modification of aerosil surface by hydrophobic fragments improves these characteristics. Also the dependence of a hydrophobic modificator structure on electro-optical characteristics was investigated. Explanation is given on the basis of the influence of the surface structure on the anchoring energy value of the LC-aerosil interface.

23.4: Electro-Optic Properties of Ferroelectric Nanoparticle / Liquid Crystal Dispersions

We enhance the electro-optic performance of liquid crystals by dispersing ferroelectric nanoparticles. Devices using these dispersions have lower driving voltages, faster switching speeds and higher contrast ratios. These changes are caused by increases in the dielectric anisotropy, birefringence and elastic constants and can be used to produce improved displays.

Non-monotonic exposure dependence of the pretilt angle and surface polarity of the photo-orientant F-PVCN

We report on the first observation of a non-monotonic UV exposure dependence of the pretilt angle of a liquid crystal on a photoaligning surface. We found this non-monotonic dependence on fluorinated poly(vinyl cinnamate) (PVCN-F) surface while non-fluorinated PVCN revealed a monotonic decrease of the pretilt angle with exposure. These dependences correlate with light-induced changes of the polarity of PVCN-F and PVCN surfaces. The obtained data point to an important role of the surface polarity and the light-induced changes in mechanisms of pretilt angle generation on photoaligning materials.