Polymer ultrathin films via alternate self-assembly adsorption of polyelectrolyte and azo-dye molecules: Photo-induced alignment and LC display properties

In this report, we describe the fabrication and photo-induced alignment of ultrathin films of small molecular azobenzene dyes and polyelectrolytes using the alternate polyelectrolyte deposition (APD) technique. The molecular self-assembly process were investigated by QCM, ellipsometry, UV-vis spectroscopy, X-ray reflectometry, and other surface sensitive spectroscopic and microscopic methods to correlate with film formation parameters. The importance of layer order;pg and dye aggregation phenomena is emphasized. We then utilized polarized UV-light to induce photo-alignment of these ultrathin films and observed high anisotropies dependent on the dye, layer preparation and thickness. Fabrication of hybrid LC cells using a nematic LC reveal that in-plane homogeneous alignment is influenced by the anisotropy of the dye aggregates.