Shear-induced optical anisotropy in a Langmuir monolayer: a Brewster anglereflectivity study

Under shear, some specific films present an in-plane molecular alignment. A ssuming that the optical property of a such monolayer is similar to that of a 2D nematic liquid crystal, we demonstrated that shearing the initially i sotropic film by a rotating disk can lead to an optical anisotropy at the i nterface. Theoretically, the Brewster angle microscopy image of the monolay er appears like a distorted extinction cross. Experimentally, reflectivity measurements on a mesogenic polyacrylate monolayer fit well the model and s hows for the first time shear induced optical anisotropy. (C) 1999 Elsevier Science S.A. All rights reserved.