Location: CREOL Room 102, University of Central Florida

11:00 am to 12:00 pm, Seminar I: Liquid crystalline AF and F materials: state of arts and own research and achievements

Speaker: Professor Roman Dabrowski

Abstract:

Development trends in ferroelectric and antiferroelectric liquid crystal (LC) materials will be presented and reviewed. The main focus will be on orthoconic antiferroelectric materials. Especially the relationship between their structures and the properties will be discussed.

Biography:

Roman Dąbrowski is currently full professor of organic chemistry and director of the Institute of Chemistry at Military University of Technology (MUT), Poland. He received his Ph.D (1966) and Sc.D (1970) from MUT on organic semiconductors. His current research is mainly on new LC materials for displays and photonic applications. He was a member of Scientific and Organizing Committees of International Liquid Crystal Conferences and a recipient of the Frederick's Medal.

 Pizza and refreshment will be served at noon!

 1:00 pm to 2:00 pm, Seminar II:  Determination of Anchoring Energy, Diamagnetic Anisotropy and Elasticity of Some Nematics

Speaker: Professor Zbigniew Raszewski

Abstract:

Reliable wedge cells with wedge angles at an order of few milliradians are filled with nematic liquid crystals of planar or homeotropic alignments to measure their threshold electric and magnetic fields for Fréedericksz transitions under crossed polarizers. In the vicinity of each interference fringe observed, a cell could be considered as flat-parallel and hence it is equivalent to a system of flat cells of varying thickness that can be precisely determined. The threshold field magnitudes are interpreted as the eigenvalues of a boundary eigenvalue problem for the operator at the second derivative; the interaction between the nematics and the substrates is described by the Rapini-Papoular formula or by a polynomials. The resulting formulae is used to determine the anisotropy of diamagnetic susceptibility and the splay and bend elastic constants of a few nematic liquid crystals (5CB, 6CHBT, DE) and their polar anchoring energy coefficients. The estimates of material parameters agree pretty well with data taken from literature, which provides a promising method in characterizing LC materials.

Biography:

Zbigniew Raszewski is currently a full professor of applied physics and director of the Institute of Applied Physics at MUT, Poland. His current research is focused on ferro and antiferroelectric liquid crystals. The physical and electro-optical properties of this class of liquid crystals still require a lot of basic research before application stage.

For more information, please contact us by zge@mail.ucf.edu