ATOMISTIC COMPUTER SIMULATIONS OF TERRACED WETTING OF MODEL 8CB MOLECULES AT CRYSTAL SURFACES

Abstract

Results are shown from computer simulations of droplets of model 8CB-like liquid crystal molecules in contact with a crystal surface. It is shown that the type of wetting observed depends on the strength of the interaction energy between the liquid crystal molecules an the substrate. For a low energy surface, partial wetting is found, and the liquid crystal forms a sessile droplet. However, for higher energies, the droplet spreads rapidly, forming a percursor layer and clearly defined molecular terraces. These results are qualitatively in line with experimental findings. The dynamics of spreading of the precursor layer have been examined, and the experimentally observed proportionality of the film radius on √t has been reproduced. However, on examining the structure of the spreading layer, it is found that, at temperatures corresponding to a bulk smectic A phase, the spreading layer has a diamond shape, with edges perpendicular to the [110] directions in crystal surface. At higher temperatures, when the bulk system is in the isotropic phase, the spreading layer reverts to a radial symmetry.

Keywords:

• 4′-n-octy 1-4-cyanbipheny1
• computer simulation
• liquid crystal
• terraced wetting