Close to the interface between a nematic liquid crystal (NLC) and another medium, the elastic constants become functions of distance z from the interface and of angle theta between the director n and the unit vector k orthogonal to the interface. Furthermore, due to the breaking of the translation symmetry at the interface, a lot of new subsurface elastic contributions can appear. In a previous paper we investigated these subsurface anomalies by using a simple molecular model based on induced-dipole-induced-dipole interactions and by making numerical calculations in the special case of a planar director distortion. In this way, only the numerical values of some effective subsurface elastic constants that characterise planar director distortions could be obtained. In this paper we make a more complete analytical calculation of all the subsurface elastic constants by using a microscopic model and a more general theoretical procedure. The microscopic interaction energy is written in a general form that allows us to investigate different kinds of intermolecular interactions (induced dipole-induced dipole, quadrupole-quadrupole and so on). Both the x-dependence and the theta-dependence of the subsurface elastic constants are obtained in a closed analytical form. In the special case of induced-dipole-induced-dipole interactions and for planar director distortions, our analytical results are shown to agree with the previous numerical results. The important macroscopic effect of these elastic subsurface anomalies is discussed.
|Autori interni:||FAETTI, SANDRO|
|Autori:||FAETTI S; RICCARDI M|
|Titolo:||ELASTIC-CONSTANTS IN THE INTERFACIAL LAYER AT THE NEMATIC-LIQUID-CRYSTAL VAPOR INTERFACE|
|Anno del prodotto:||1995|
|Digital Object Identifier (DOI):||10.1007/BF02456790|
|Appare nelle tipologie:||1.1 Articolo in rivista|