Oscar R. Santos, Wladimir S. Braga, Danilo D. Luders, Newller M. Kimura, Manuel Simões, Antonio J. Palangana

Journal of Molecular Liquids – Volume: 200, Part B; Pages: 319–322; DOI:10.1016/j.molliq.2014.10.019

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°.