Atomistic modelling of liquid-crystal surface modification

Results are shown from atomistic molecular-dynamics simulations of 800 5CB molecules in contact with a graphite substrate, onto which flexible alkyl chains have been tethered. By increasing the number density of tethered chains, it is shown that the alignment switches from planar to homeotropic. The change of anchoring is accompanied by a change in the conformation of the tethered chains, which switch from being bound close to the substrate at low densities, to being almost fully extended and parallel to the liquid-crystal moieties at high densities.