Microscopic understanding of the complex polymer dynamics in a blend —A molecular-dynamics simulation study

¹ University of Münster, Institute of Physical Chemistry - Corrensstrasse 28/30, D-48149 Münster, Germany, EU
² NRW Graduate School of Chemistry - Corrensstrasse 36, D-48149 Münster, Germany, EU
³ Jülich Center for Neutron Science & Institute for Complex Systems, Forschungszentrum Jülich GmbH D-52425 Jülich, Germany, EU

^a d.diddens@uni-muenster.de

Received: 15 June 2011
Accepted: 14 July 2011

Abstract

Within polymer blends composed of two species with largely different glass transition temperatures like PEO/PMMA, the dynamics of the fast PEO component is severely affected by the rather immobile PMMA, reflected by a breakdown of the typical Rouse scaling. The phenomenological random Rouse model (RRM), in which each monomer has an individual mobility obeying a broad log-normal distribution, has been applied to these blends. Using a newly developed method, we extract the distribution of friction coefficients from MD simulations of a PEO/PMMA blend, thereby testing the RRM explicitly. In our simulations we observe that the distribution is much narrower than expected from the RRM. Here, rather, the presence of additional forward-backward correlations of intermolecular origin is responsible for the anomalous PEO behavior.