Experimental study of prewetting transitions by systematic variation of the surface field at nematic liquid crystal/water interfacesCh. Bahr
Max Planck Institute for Dynamics and Self-Organization - Bunsenstr. 10, D-37073 Göttingen, Germany, EU
received 7 October 2009; accepted in final form 6 November 2009; published November 2009
published online 2 December 2009
An ellipsometric study of the interface between a nematic liquid crystal and water in the presence of a nonionic surfactant is presented. The surfactant induces a nematic wetting layer at temperatures above the bulk nematic-isotropic transition and the surfactant concentration serves as a handle to tune the strength of the ordering surface field. At low surfactant concentrations, a discontinuous jump in the thickness of the nematic wetting layer is observed at a temperature a few tenth of one centigrade above the bulk nematic-isotropic transition. With increasing surfactant concentration, this prewetting transition is driven towards a critical point.
61.30.-v - Liquid crystals.
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.
68.05.Cf - Liquid-liquid interface structure: measurements and simulations.
© EPLA 2009