Berlin 2008 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 10: POSTERS New Materials, Organic Semiconductors
CPP 10.1: Poster
Monday, February 25, 2008, 16:45–19:00, Poster A
Optical properties of Biaxial Nematogens — •David Polster1, Christiane Köhn2, Jens Seltmann2, Matthias Lehmann2, Harald Graaf1, Jörg Schuster1, and Christian von Borczyskowski1 — 1Center of Nanostructured Materials and Analytics, TU Chemnitz, 09107 Chemnitz, Germany — 2Juniorprofessur Nichtklassische Synthesemethoden, TU Chemnitz, 09107 Chemnitz, Germany
Typical liquid crystalline molecules (nematogens) are characterized by a linear shape with one permanent dipol and are known to form a nematic phase. In biaxial nematogens (V-shaped molecules) instead two perpendicular dipoles can be found. For such mesogens the tendency to form the so illusive biaxial nematic phase is proposed for which up to 100fold faster switching times are expected.
We will present here a new class of unsymmetric substituted V-shape molecules. These mesogens consists of a bent core which defines the dihedral angle of the V-shaped molecule and two rigid arms with cyano substituted terminal aromatic units. They are characterized by two different dipole moments along the short and the long molecular axis. The thermotropic behavior of these new materials has been investigated and its nematic phase was characterized. The orientation of the nematogens in a typical liquid crystal cell will be shown and the influence of an applied electric field will be discussed. An alignement along the short axis of the molecule under electric field plays the major role for low voltages.