Photo-Induced Anisotropy of Methyl Red Azo Dye in Polymer Film

A photo-induced anisotropy (PIA) of Methyl Red (MR) azo dye embedded in PMMA polymer solid films was investigated by studying dichroic spectra and photo-induced birefringence. The reversible PIA of MR dye was measured in situ during photoactive irradiation process. Photoinduced order increases with the rise of exposure power. It is shown that PIA dark relaxation slows down at higher exposure energy. The MR rotational diffusion was evaluated at different exposure modes. These data are useful for the characterization of Methyl Red azo dye as a liquid crystal photo-aligning material.