Defects and textures of hexagonal discotics

Y. Bouligand

Defects and textures were studied in the discotic mesophases formed by an hexa-alkoxy-triphenylene (the pentyl derivative). Two main textures are distinguished, with molecular stacks lying mainly vertical or horizontal. The vertical texture is more frequent between slide and coverslip; the second one is favoured by the air-interface (drop with a free upper surface). Both textures are built around + π or + 2 π disclinations lying either horizontally in vertical textures or conversely. There are two different kinds of walls, corresponding either to a discontinuity of crystallographic axes or to a discontinuity of curvature. Germs of vertical textures present an outline with the symmetries of the hexagonal order of the molecular columns. The origin of the + π disclinations bhas been analysed in horizontal textures. A model is proposed for the textures submitted to a shear.

Mots clés: disclinations; liquid crystals; organic compounds

Domaines: Articles anciens

Y. Bouligand. Defects and textures of hexagonal discotics. Journal de Physique, 1980, 41 (11), pp.1307-1315. ⟨10.1051/jphys:0198000410110130700⟩. ⟨jpa-00208958⟩