Berlin 2001 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 1: Special Symposium: Molecular Dynamics in Confined Geometries
CPP 1.5: Hauptvortrag
Montag, 2. April 2001, 15:45–16:30, 3010
Molecular Dynamics Studies of Glassforming Fluids in Confined Geometry — •Kurt Binder1, Fathollah Varnik1, Peter Scheidler1, Jörg Baschnagel2, and Walter Kob3 — 1Institut für Physik, Johannes Gutenberg-Universität, Staudinger Weg 7, D–55099 Mainz, Germany — 2Institut Charles Sadron, ULP, 67083 Strasbourg, France — 3Laboratoire des Verres, Université Montpellier II, 34000 Montpellier, France
The investigation of the glass transition of supercooled fluids in macroscopic cylindrical pores or in thin films can elucidate the cooperative character of the glass transition. However, the interpretation of the changes in comparison with the behavior of the bulk material is subtle. Depending on the nature of the confining surfaces either an increase or a decrease of the glass transition temperature can occur. These considerations are exemplified with two models. In model I, a melt of flexible short polymer chains is described in terms of a bead-spring model, and the confining geometry is realized by two parallel smooth repulsive walls. This boundary condition leads to a decrease of the glass transition temperature. The opposite behavior occurs in model II, a binary Lennard-Jones mixture confined by atomistically rough walls formed from the same material. Consequences for the interpretation of experiments in real materials are briefly discussed.