CHARACTERIZATION BY MIRAGE EFFECT TECHNIQUE OF DYE DIFFUSION IN COLUMNAR DISCOTIC LIQUID-CRYSTALS

The anisotropic behaviour of the matter diffusion in columnar discotic liquid crystals is studied by the 'mirage effect' technique. The D-h and D-0 mesophases of C(8)HET and C(11)HET, respectively, are consider ed. The impurity (a dye, the 1-[4-(xylylazo)xylylazo]-2-naphthol) diff using in these mesophases is detected by the photothermal deflection t echnique. Measurements of the diffusion coefficients are performed in two perpendicular directions, along and perpendicularly to the molecul ar columns. Effects of impurity size, length and type of the branched chains on the discs of triphenylene, and molecule stackings in columns , are presented.