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DY: Dynamik und Statistische Physik
DY 16: Growth Processes and Surface Properties
DY 16.7: Vortrag
Montag, 27. März 2006, 17:45–18:00, H\"UL 186
The isotropic-nematic interface in suspensions of platelets — •Tanja Schilling1, Paul van der Schoot2, and David van der Beek3 — 1Institut für Physik, Johannes Gutenberg-Universität, 55099 Mainz, Staudinger Weg 7, Germany — 2Eindhoven University of Technology, Applied Physics, PO Box 513, 5600 MB Eindhoven, The Netherlands — 3Van ’t Hoff Laboratory for Physical and Colloid Chemistry, Utrecht University, 3584 CH Utrecht, The Netherlands
Suspensions of plate-like particles phase separate into an isotropic and a nematic phase at sufficiently high concentrations. The reasons for this are identical to those for the formation of a nematic phase in suspensions in rod-like colloids: a strongly anisotropic excluded-volume interaction between the particles favours parallel alignment. However, there is a crucial difference between the nematic ordering of rods and platelets: Rods may be quantitatively understood at the level of second virial theory whereas this is not the case for platelets. Presumably this is the reason why in the theoretical literature so much more emphasis has been on nematics of rods than on that of platelets. Also, experimentally it seems to be easier to supress gelled states in rod dispersions than in plate ones. Recently, however, significant progress in the experimental study of suspensions of platelets has been made, making it timely to consider the issue in more detail.
We present a combined theoretical, simulational and experimental study of the isotropic-nematic interface. In particular, we show that its interfacial tension can be extracted from the capillary rise of the interface without knowledge of the elastic constants of the nematic phase.