Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 49: Polymer Dynamics I

CPP 49.1: Vortrag

Donnerstag, 3. April 2014, 17:00–17:15, ZEU 260

Modeling high-molecular weight polymer melts: equilibration and rheological properties — •Livia Moreira, Guojie Zhang, Torsten Stuehn, Kostas Daoulas, and Kurt Kremer — Max Planck Institute for Polymer Research, Mainz

A modeling strategy is developed for studying rheological properties of high-molecular weight polymer melts described with microscopic detail. The microscopic model is generic but retains hard excluded volume interactions and realistic densities. Equilibrated configurations are generated by a backmapping strategy using a coarse-grained (CG) model representing polymer chains as strings of fluctuating blobs [1,2]. Each stands for one subchain of N_b microscopic beads. Varying N_b, a hierarchy of CG models with different resolutions is obtained. Within this hierarchy, CG configurations equilibrated at low-resolution are sequentially fine-grained into melts of higher resolution. Microscopic details are then introduced modifying the scheme of Auhl et al [3]. Backmapping involves only local polymer relaxation, thus the method is independent of chain length. This strategy is implemented to equilibrate melts with different persistence lengths and polymerization degrees up to 55 entanglement lengths, N_e. The N_e is quantified using primitive path analysis and effects of finite system-size and chain length are discussed. A master curve for the estimating N_e for different chain lengths and persistence lengths is provided. We comment on alternative estimations of N_e, e.g., from plateau modulus analysis. [1] Vettorel et al, Soft Matter (2010) 6, 2282 [2] Zhang et al, Macromol. Chem. Phys. (2013) 214, 214 [3] Auhl et al, J. Chem. Phys. (2003) 119, 12718