Photo-induced fabrication of surface relief gratings in alternate self-assembled films containing azo dye and alignments of LC molecules

Photo-induced surface relief gratings of alternate layer-by-layer self-assembled films containing azobenzene dyes were fabricated. The alignment properties of nematic liquid crystal (LC) molecules on these films were investigated in a hybrid LC cell configuration. Poly(diallyldimethylammonium chloride) (PDADMAC) and Direct Red 80 (DR80, azobenzene dye) were deposited using the alternate layer-by-layer self-assembly method. The gratings of the PDADMAC/DR80 films were fabricated by exposure to interference patterns of Ar⁺ laser light at 488 nm. The formation of the gratings on the films was observed using atomic force microscopy. Furthermore, the alignment properties of LC molecules, 5CB, on the films were investigated by monitoring the change in birefringence of the LC cell in situ. This in-plane alignment was observed after ∼30 min exposure with the laser, simultaneous with the formation of the interference patterns.