Chiral Discotic Colunmar Phases in Liquid Crystals

(Received 13 November 1996, received in final form 11 March 1997, accepted 18 March 1997)

Abstract
We introduce a model to describe columnar phases of chiral discotic liquid crystals in which the normals to disc-like molecules are constrained to lie parallel to columnar axes. The model includes separate chiral interactions favoring, respectively, relative twist of chiral molecules along the axes of the columns and twist of the two-dimensional columnar lattice. It also includes a coupling between the lattice and the orientation of the discotic molecules. We discuss the instability of the aligned hexagonal lattice phase to the formation of a soliton lattice in which molecules twist within their columns without affecting the lattice and to the formation of a moiré phase consisting of a periodic array of twist grain boundaries perpendicular to the columns.