Liquid-crystal anchoring transitions on aligning substrates processed by a plasma beam.

We have studied a sequence of anchoring transitions observed in nematic liquid crystals (NLCs) sandwiched between hydrophobic polyimide substrates treated with a plasma beam. There is a pronounced continuous transition from a homeotropic to a slightly tilted (nearly planar) alignment with the easy axis parallel to the incidence plane of the plasma beam (the zenithal transition) which takes place as the exposure dose increases. In NLCs with positive dielectric anisotropy, a further increase in the exposure dose results in in-plane reorientation of the easy axis by 90 degrees (the azimuthal transition).

Electro-optics and structural peculiarities of liquid crystal-nanoparticle-polymer composites.

The structural peculiarities and electro-optic performance of liquid crystal (LC)-colloidal nanoparticle (NP)-polymer (P) composites formed by photoinduced phase separation are considered. We classify these materials under two groups according to two limiting cases of polymer morphology. The first group corresponding to small polymer concentration comprises LCs filled with NPs that are stabilized with a polymer network.