Coupling between the nematic/isotropic transition and a thickness transition: A theoretical approach

Abstract

In this letter, we develop a theoretical model of the effect of a free surface on the nematic-to-isotropic phase transition in a confined geometry. Simply by coupling a bulk first-order phase transition with a thickness-dependent elastic distortion field in a Landau-like description, the model predicts a coexistence at equilibrium between the isotropic and the nematic phases at two different thicknesses. A phase diagram is constructed in the temperature-thickness plane and a comparison is given with experimental results obtained on thin films (van Effenterre D., Ober R., Valignat M. P. and Cazabat A. M., Phys. Rev. Lett.87(2001) 125701).