MSE Seminar - Dr. Mohan Srinivasarao - MSE, Georgia Tech
Dr. Mohan Srinivasarao
School of Materials Science and Engineering
Georgia Institute of Technology
Monday, February 20, 2017
4:00 p.m. GTMI/Callaway Bldg. Auditorium
Reception at 3:30 p.m. in the GTMI Atrium
" Spontaneous Emergence of Chirality from Achiral Systems: The Case of Lyotropic Chromonic Liquid Crystals"
I will explore the spontaneous emergence of chiral structures from achiral lyotropic chromonic liquid crystals when confined to cylindrical capillaries with various boundary conditions. When confined to a cylindrical geometry with planar boundary conditions, the presumed ground state of a nematic fluid corresponds to that of an axial configuration, where the director, free of deformations, lies along the long axis of the cylinder. However, upon confinement of lyotropic chromonic liquid crystals in cylindrical geometries, we uncover a surprising ground state corresponding to a doubly twisted director configuration. The stability of this ground state, which involves significant director deformations, can be rationalized by the saddle-splay contribution to the free energy. It will be shown that sufficient anisotropy in the elastic constants drives the transition from a deformation-free ground state to a doubly twisted structure, and results in spontaneous reflection symmetry breaking with equal propensity for either handedness. Enabled by the twist angle measurements of the spontaneous twist, we determine the saddle-splay elastic constant for chromonic liquid crystals. I will also discuss the path to a monodomain or a single crystal, if you will, of chrominc liquid crystals confined to a rectangular capillary enabled by a spontaneous twist deformation.
Dr. Mohan Srinivasarao is a Professor with the School of Materials Science and Engineering. Dr. Srinivasarao received his Ph.D. in Chemistry in 1990 from Carnegie Mellon University, a M.Sc in Applied Chemistry in 1981 from PSG College of Technology (University of Madras, India), and a B.Sc in Applied Science in 1979 from Madurai University, India.
Dr. Srinivasarao specializes in physical chemistry of polymers, physics of nematic liquid crystals, optics of liquid crystals, rheology/rheo-optics of polymeric fluids and liquid crystals, polymer/liquid crystal dispersions, various forms of light microscopy including confocal microscopy and photon tunneling microscopy, color science, and nano-optics in the biological world (color of butterfly wings, beetles, moths, and bird feathers).
Dr. Srinivasarao is a member os several professional organizations including the American Chemical Society, Materials Research Society, Optical Society of America, Society of Rheology, American Physical Society, and the American Association for the Advancement of Science. He has published several articles and papers in a variety of journals.