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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 17: Confined Fluids

CPP 17.8: Vortrag

Dienstag, 24. März 2009, 11:30–11:45, ZEU 160

Deformation of nanoporous materials during the sorption process — •Gerrit Günther and Martin Schoen — Stranski-Laboratorium für Physikalische und Theoretische Chemie, Sekretariat C7, Technische Universität Berlin, Straße des 17. Juni 135, D-10623 Berlin, Germany

Several experiments point at deformations of nanopores due to the sorption of confined fluids. To investigate such strains and their influence on phase behavior of the confined fluid we use the grand canonical ensemble Monte Carlo method (GCEMC). We consider a simple fluid between two plane parallel walls which themselves consist of single wall particles. Wall and fluid particles are of the same type and are interacting via Lennard-Jones(12,6) potentials. The wall particles are not fixed to their lattice sites but bound to them by harmonic potentials. Thus we are able to control the softness of the wall via the force constant of this harmonic potential from an almost rigid structure to more flexible walls. Flexible means that the wall atoms can move from their equilibrium positions to react to the fluid. Despite a shift of fluid phase transition flexible pores reveal a typical sequence of pore deformations during the sorption process even in the critical regime. It is remarkable that strains of our slit pore model are in good agreement with experimental results of cylindrical pores. [1] This suggests that dispersion forces rather than curvature effects are responsible for pore deformation.
[1] G. Günther, J. Prass, O. Paris, and M. Schoen, Phys. Rev. Lett. 101 (2008), 086104.