Alignment behavior of discotic nematic and rectangular columnar mesophases on self-assembled monolayers of alkanethiol and asymmetrical alkyl disulfide

Alignment behavior of a discotic liquid crystalline triphenylene (C80BTP) on substrates coated with self assembled monoloyers (SAMs) of alkanethiol and asymmetrical alkyl disulfide was investigated by polarized microscopy. Discotic nematic (N-D) and rectangular columnar (Col(r)) phases of C80BTP shows a different alignment behavior depending on the element of SAMs. C80BTP exhibits a fan-shaped texture on an alkanethiol SAM in Col(r) phase, while it has a tendency to show a planar alignment on asymmetrical alkyl disulfide SAM. The different elements of the SAM could influence the alignment behavior of discotic liquid crystal distinctly even in columnar mesophase which has highly self-cohesive forces of systems.