Pabitra Datta

Alignment and wetting properties of nematic liquid crystals on plasma-polymerized films

Abstract The polar and dispersive components of the surface energy of nematic liquid crystals were calculated from contact angle measurements on a variety of polymeric films with known surface energies using the Kaelble-Good-Girifalco-Fowkes equation. The orientation of liquid crystals on plasma-polymerized films with a wide range of surface energies was studied. A relationship between the spontaneous spreadability criteria calculated from surface energy and liquid crystal orientation was observed. In general, a negative spreadability coefficient of a liquid crystal on a plasma-polymerized film indicates perpendicular alignment and a positive spreadability coefficient predicts parallel alignment. The measured critical surface energy of the plasma-polymerized films varied widely depending upon the choice of solvent used, and no relationship was observed between this value and liquid crystal orientation.