SURFACE TENSIONS AND ANCHORING TRANSITIONS OF NEMATIC LIQUID-CRYSTALSON GRADUALLY OXIDIZED SUBSTRATES

Intermediate anchorings of nematic liquid crystals onto substrates no now intensively studied essentially because of their potential display applications. Here, we use the active oxygen gas arising from a plasm a reactor to realize progressive chemical modifications of glass subst rates covered with silane. In this manner, the dispersive and nondispe rsive surface tensions of the substrate are gradually modified involvi ng a continuous change in the differential wetting properties of the s ubstrate with both parts of the liquid crystal molecules, and in the a nchoring energy. Intermediate anchorings with tilted angles are thus o btained in the vicinity of an anchoring transition from the pseudohome otropic to the planar alignment, where symmetry is broken. (C) 1997 Am erican Institute of Physics.