Role of Delocalized Electrons in Polyaniline−Nematogen Cyanobiphenyls Interaction

Abstract

Applying an electric field across a nematic liquid crystal display changes the texture of the thin nematic film. When the field is switched off, the texture relaxes to the initial one within seconds. Experimental evidence that very fast relaxation times could appear in some particular cases is reported. A thin film of plasma polymerized aniline induces a stronger planar anchoring of cyanobiphenyl liquid crystals. This strong anchoring appears when, due to an asymmetric conduction of the liquid crystal cell, alternating voltages create a transient electrically charged layer at the polyaniline/liquid crystal interface. This layer favors an expansion of anchoring toward the bulk, thus lowering dramatically the relaxation time and increasing the contrast ratio.