Alignment of Liquid Crystals by Amphiphilic Monolayers

Abstract

The action of solid surfaces coated with monomolecular films of amphiphilic compounds (especially lecithins) on adjacent liquid crystal phases resulting in an uniform homeotropic orientation has been investigated. The quality of orientation was found to be effected by molecular structure of the amphiphilics as well as the liquid crystals, the packing density of the film, and the temperature. The experimental results can be understood in terms of the following model: Lecithins form brush‐like films with the hydrophobic alkyl chains pointing off the glass surface. Under suitable conditions holes of molecular dimensions exist in the films into which nematogenic molecules can penetrate. By means of elastic interaction forces between these anchored molecules and the adjacent nematic bulk the homeotropization is induced.

Chemical and biological sensing using liquid crystals

“…Fluorescence recovery after photobleaching (FRAP) experiments also revealed that the phospholipids at the interface were laterally mobile, exhibiting diffusion coefficients that were comparable to those measured within lipid bilayers. The homeotropic orientation assumed by the LC at the lipid-decorated interface was interpreted to be due to molecular interdigitation of the tails of the phospholipids and the mesogens forming the LC, a conclusion that is supported by a number of early studies on the interactions of LCs and lipids supported on solid surfaces (Langmuir-Blodgett films of lipids) [60]. …”

Self-assembly of surfactants and phospholipids at interfaces between aqueous phases and thermotropic liquid crystals

“…1 been deposited [11][12][13][14][15]. First, the thermodynamic states of the amphiphiles at these interfaces differ from each other: at equilibrium, the chemical potential of a surfactant in a surfactant-laden aqueous-liquid crystal interface is determined by the composition of the surfactant in the bulk aqueous phase.…”

Surface-Induced Flexoelectric Domains in Asymmetrically Strong-Weak Anchored MBBA Films

“…Asymmetrically-anchored MBBA layers were prepared as well with one aliphatic monoamine C8H17NH2 layer deposited by means of the wellknown drawing technique allowing the adsorbtion of one or several monomolecular films [23], [24], [25]. In cells prepared in such a way we observed only 0-hydrodynamic instabilities without any Pig.…”