Prof. Dr. Lou Kondic (NJIT): Instabilities and dewetting of thin nematic liquid crystal films

Partially wetting nematic liquid crystal (NLC) films on substrates are unstable to dewetting-type of instabilities due to destablizing solid/NLC interaction forces. These instabilities are modified by the nematic nature of the films, which influences the effective solid/NLC interaction. In the present talk, after reviewing general features of instability development, we focus on the influence of imposed substrate anchoring. The analysis is carried out within long-wave formulation based on the Leslie-Ericksen description of NLC films. Linear stability analysis of the resulting equations shows that some features of the instability, such as emerging wavelengths, may not be influenced by the imposed substrate anchoring. Going further into the nonlinear regime, considered via large-scale GPU-based simulations, shows however that nonlinear effects may play an important role, in particular in the case of strong substrate anchoring anisotropy. Our simulations show that the film instability develops in two stages: the first stage involves formation of ridges that are perpendicular to the local anchoring direction; and the second involves breakup of these ridges. Finally, we will discuss possible connections of our results to physical experiments and applications.