8th Liquid Matter Conference September 6-10, 2011 Wien, Austria ...

Fri 911:10-14:00P3.7Filling and wetting transitions of nematic liquid crystalon rectangular grated surfacesZahra Eskandari, 1 Nuno M Silvestre, 1 Pedro Patricio, 2 Jose M Romero-Enrique, 3and Margarida M Telo da Gama 41 Centro de Fisica Teorica e Computacional, Av. Prof. Gama Pinto, 2, 1649-003, Lisboa,Portugal2 Instituto Superior de Engenharia de Lisboa, Lisboa, Portugal3 Departamento de Fisica Atomica, Molecular y Nuclear, Universidad de Sevilla, Sevilla,Spain4 Departamento de Física, Faculdade de Cincias da Universidade de Lisboa, Lisboa,PortugalAlthough of considerable fundamental interest, with relevant applications in bistable liquid crystaldisplays, nematic interfacial phenomena at structured surfaces has attracted little attention. Herewe present our findings for wetting phenomena of nematic liquid crystals at castellated walls.The interplay between elasticity, surface anchoring, and topography leads to phenomena differentfrom observed for simple fluids. We will show that, while for low roughness there is only dry towet transition, at high roughness the wetting transition is completely suppressed and the systemexhibits only dry to filling transition. In particular, we will show that for intermediate roughness,and under certain conditions, the dry → filling → wet sequence, usual to simple fluids, can giveway to re-entrant phenomena where the system re-enters the filling state as a way to prevent thenucleation of topological defects.7