Computer simulation of bottle-brush polymers with flexible backbone: Good solvent versus theta solvent conditions

Author(s): Panagiotis Theodorakis, Hsiao-Ping Hsu, Wolfgang Paul, Kurt Binder
Abstract: By Molecular Dynamics simulation of a coarse-grained bead-spring type model for a cylindrical molecular brush with a backbone chain of Nb effective monomers to which with grafting density σ side chains with N effective monomers are tethered, several characteristic length scales are studied for variable solvent quality. Side chain lengths are in the range 5≤N≤40, backbone chain lengths are in the range 50≤Nb≤200, and we perform a comparison to results for the bond fluctuation model on the simple cubic lattice (for which much longer chains are accessible, Nb≤1027, and which corresponds to an athermal, very good, solvent). We obtain linear dimensions of side chains and the backbone chain and discuss their N-dependence in terms of power laws and the associated effective exponents. We show that even at the Theta point the side chains are considerably stretched, their linear dimension depending on the solvent quality only weakly. Effective persistence lengths are extracted both from the orientational correlations and from the backbone end-to-end distance; it is shown that different measures of the persistence length (which would all agree for Gaussian chains) are not mutually consistent with each other, and depend distinctly both on Nb and the solvent quality. A brief discussion of pertinent experiments is given.
Organisation(s): Computational and Soft Matter Physics
External organisation(s): Johannes Gutenberg-Universität Mainz, Martin-Luther-Universität Halle-Wittenberg
Journal: Journal of Chemical Physics
Volume: 135
No. of pages: 13
ISSN: 0021-9606
DOI: https://doi.org/10.1063/1.3656072
Publication date: 2011
Peer reviewed: Yes
Austrian Fields of Science 2012: 103005 Atomic physics, 103018 Materials physics
Portal url: https://ucrisportal.univie.ac.at/en/publications/a0211adb-589b-41bf-a0bc-c030d4e33808