Conoscopic image of an induced biaxial nematic lyotropic phase

Recently, it has been shown by Lavrentovich and co-workers that when a uniaxial nematic thermotropic is subjected to a thermal expansion, the resulting fluid flow can create textures that produce conoscopy images similar to those used to characterize biaxial samples. This works aims to provoke a thermal expansion in a uniaxial discotic nematic lyotropic and compare the resulting conoscopic image with the one obtained in a biaxial nematic phase widely known in lyotropic materials. Our experimental results show that they are perfectly distinguishable; the thermal expansion really leads to a biaxial nematic conoscopic image, but the orientation of the optical axes is rotated by 90 degrees. (C) 2014 Elsevier B.V. All rights reserved.