Characteristics of oriented dye films on command surfaces

Abstract

We have reported that anisotropic orientation of dichroic dye molecules is induced by a thin film of a poly(methacrylate) containing azobenzene units as side chains. A polymer film was exposed to linearly polarized light in order to induce anisotropic photoisomerization of azobenzene units. The anisotropic ordering of azobenzene was transferred to a uniaxial alignment of dye molecules by spin-coating of an aqueous solution of dye containing a surfactant. The orientation direction of dye molecules was the same as the direction of an electric vector of polarized light inducing the photoisomerization. In this work, we measured dichroic absorption spectra of oriented dye films with a microscopic spectrometer and observed their morphology with AFM and SEM. We found that order-parameters of microscopic regions are much superior to that of macroscopic ones. In-plane alignment control of dye molecules with various concentration of surfactant was also studied.