3:00 pm in Howey Lecture Room 5 (pre-reception at 2:30 in Howey N201)
Oleg D. Lavrentovich
Liquid Crystal Institute and Chemical Physics Interdisciplinary Program
Kent State University
"Dynamics of liquid crystal colloids studied by 3D microscopy"
Liquid crystals (LCs) produce a rich variety of complex 3D structures that are easily changed by external fields, boundary conditions, embedded particles, etc. In the latter case of a liquid crystal with colloidal inclusions (liquid crystal colloid), the equilibrium is often achieved by introducing topological defects in the director field, stabilized by surface anchoring at interfaces. This report presents recent experiments on the dynamics of micron-size colloids in the nematic and smectic liquid crystals driven by AC and DC electric fields. The 3D director structure around the particles is visualized by fluorescence confocal polarizing microscopy (FCPM). The electric field causes translation and rotatio of the colloids. The underlying mechanisms include specific liquid crystal effects such as backflow (coupling of director reorientation and mass flow) and mechanisms of general nature, such as electrophoresis, electrorotation, and hydrodynamic interaction between the particle and a confining wall. These general mechanisms acquire new, sometimes unexpected, facets when the action is staged inside a liquid crystal. The work supported by NSF DMR, DOE, W.M. Keck Foundation, CMPND.
