Biaxial model of the surface anchoring of bent-core smectic liquid crystals - art. no. 031706

In synclinically tilted smectic phases, bent-core liquid crystal molecules aligned with the director in the plane of a cell boundary will, in general, have their molecular (bow) planes parallel to the boundary, normal to it, or at a well-defined intermediate orientation. A model describing the inter action of such bent-core (banana-shaped) molecules with planar surfaces tha t distinguishes energetically between molecules lying flat on the surface a nd those oriented edge on is given by a biaxial modification of the uniaxia l surface anchoring expression used for chiral smectics of rod-shaped molec ules. When combined with a field-induced straightening of the smectic layer s, the model provides a mechanism for the transition from an analog to a bi stable director response observed electro-optically in the ferroelectric ba nana-shaped material (R,S)-MHOBOW.