Electro-Optical Memory Effects of Polymerized Methacrylate/Liquid Crystal Systems

Abstract

The effect of the chemical structure of the initial species on the electro-optical properties of polymer/liquid crystal (LC) films was investigated. The latter were prepared by polymerizing/crosslinking reactions of low molecular weight LC/monomer blends involving irradiation processes. Several selected methacrylates as monomers and a pure nematic LC (4-cyano-4’-pentylbiphenyl = “5CB”) were mixed together where the LC to monomer ratio was taken as 7:3 and 6:4.

The electro-optical properties of the obtained phase separated polymer/LC blends were measured as function of the choice of the monomer, sample composition and applied sinusoïdal voltage of the electrical field. The transmission versus voltage curves show a strong optical memory effect for some polymer/LC systems involving especially hydroxyl and methylacrylate groups. A particular attention was paid to correlate the obtained results with sample composition and chemical nature of the monomer.

Keywords:

• Contrast ratio
• electro-optical properties
• morphology
• optical memory effect
• polymer/liquid crystal films