Eur. Phys. J. E 7, 175-182 (2002)
An anchoring transition at surfaces with grafted liquid-crystalline chain moleculesH. Lange1, 2 and F. Schmid1
1 Fakultät für Physik, Universität Bielefeld, 33615 Bielefeld, Germany
2 Institut für Physik, Universität Mainz, 55099 Mainz, Germany
(Received 5 July 2001 and Received in final form 16 November 2001)
The anchoring of nematic liquid crystals on surfaces with grafted liquid-crystalline chain molecules is studied by computer simulations and within a mean-field approach. The computer simulations show that a swollen layer of collectively tilted chains may induce untilted homeotropic (perpendicular) alignment in the nematic fluid. The results can be understood within a simple theoretical model. The anchoring on a layer of mutually attractive chains is determined by the structure of the interface between the layer of chain molecules and the solvent. It is controlled by an interplay between the attractive chain interactions, the translational entropy of the solvent and its elasticity. A second-order anchoring transition driven by the grafting density from tilted-to-homeotropic alignment is predicted.
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.
61.30.Vx - Polymer liquid crystals.
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2002