Molecular Interactions in Monolayers οf Azo Dye/Liquid Crystal Mixtures at Interfaces

Abstract

A study of azo dye/liquid crystal mixtures in monolayers formed at an air-water interface (the Langmuir films) and at a solid surface (the Langmuir-Blodgett films) has been performed. Five azo dyes with various molecular structure and the liquid crystal 4-octyl-4 -cyanobiphenyl (8CB) have been used. The dyes have been added to the liquid crystal at various molar fractions. Surface pressure and surface potential versus mean molecular area isotherms for the Langmuir films have been recorded and information about intermolecular interactions at the air-water interface has been obtained. On the basis of electronic absorption measurements for the Langmuir and Langmuir-Blodgett films the conclusions about the ability of dyes molecules to form self-aggregates at the interfaces have been drawn. The influence of the dye molecular structure and its concentration on aggregates' geometry has been found.

Intermolecular Interactions in Organic Dye Monolayers Formed by Langmuir-Blodgett Technique

“…Similar results for other perylene--like dyes and for these dyes in the Langmuir films were obtained [7]. Although for other dyes under investigation no such large differences in the shape of the spectra recorded in diluted solutions (ethanol or chloroform) and in the Langmuir and LB films were found, in all the cases the changes of the maximum position and of the half-bandwidth were observed [8][9][10][11].…”

“…The detailed results concerning the components miscibility and other parameters characterizing the Langmuir films of the dyes under investigation and of their mixtures with 7CB, 8CB or AA are presented in Refs. [7][8][9][10][11].…”