Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 19: SYMPOSIUM Driven Soft Matter IV

CPP 19.7: Vortrag

Mittwoch, 27. Februar 2008, 15:30–15:45, C 130

Thermodynamically consistent coarse-graining in unentangled polymer melts: mapping microscopic dynamics to conformation tensor theory — •Patrick Ilg, Martin Kröger, and Hans Christian Öttinger — ETH Zürich, Polymer Physics, 8093 Zürich, Switzerland

The dynamics of polymer melts both, in equilibrium and under flow is extremely interesting from a theoretical and application point of view. We here propose a systematic and thermodynamically consistent coarse-graining method that uses a combination of Monte-Carlo and molecular dynamics simulations in order to break the time-scale problem present in polymer systems. The method relies on the splitting of reversible and irreversible contributions to the dynamics and explicitly accounts for the entropy generated in the coarse-graining step. This work uses a general framework of nonequilibrium thermodynamics [1] and builds upon similar studies on the derivation of hydrodynamics for rarefied gases [2].

Starting with a classical bead-spring model of unentangled polymer melts, we coarse-grain to the frequently used conformation tensor level. We verified the method for the case of planar shear flow, where we obtain the correct viscosity and normal stress differences in the low shear rate regime.

[1] H. C. Öttinger. Beyond-Equilibrium Thermodynamics. Wiley, 2005. [2] M. Kröger and H. C. Öttinger. Beyond-equilibrium molecular dynamics of a rarefied gas subjected to shear flow. J. Non-Newtonian Fluid Mech., 120:175–187, 2004.