Anomalous structure and scaling of ring polymer brushes
Institut für Physik, Johannes Gutenberg-Universität - D-55099 Mainz, Staudinger Weg 7, Germany
2 Institute of Physical Chemistry, Bulgarian Academy of Sciences - Sofia 1113, Bulgaria
Accepted: 25 May 2011
A comparative simulation study of polymer brushes formed by grafting at a planar surface either flexible linear polymers (chain length NL) or (non-catenated) ring polymers (chain length NR=2NL) is presented. Two distinct off-lattice models are studied, one by Monte Carlo methods, the other by molecular dynamics, using a fast implementation on graphics processing units (GPUs). It is shown that the monomer density profiles ρ(z) in the z-direction perpendicular to the surface for rings and linear chains are practically identical, ρR(2NL,z)=ρL(NL, z). The same applies to the pressure, exerted on a piston at height z, as well. While the gyration radii components of rings and chains in the z-direction coincide, too, and increase linearly with NL, the transverse components differ, even with respect to their scaling properties: Rgxy(L)∝NL1/2, Rgxy(R)∝NL0.4. These properties are interpreted in terms of the statistical properties known for ring polymers in dense melts.
PACS: 82.35.Lr – Physical properties of polymers / 61.46.-w – Structure of nanoscale materials / 61.25.H- – Macromolecular and polymers solutions; polymer melts
© EPLA, 2011