Polymer absorption in dense polymer brushes vs. polymer adsorption on the brush-solvent interface

¹ Institute of Physical Chemistry, Bulgarian Academy of Sciences - 1113 Sofia, Bulgaria
² Institut für Physik, Johannes Gutenberg-Universität Mainz - Staudinger Weg 7, 55099 Mainz, Germany

Received: 28 March 2014
Accepted: 12 May 2014

Abstract

Molecular-dynamics simulations of a coarse-grained model of a dense brush of flexible polymers (of type A) interacting with a long flexible macromolecule (of type B) are presented, considering the case of an attractive AB interaction, while effective interactions between AA and BB pairs of monomers are repulsive. Varying the strength of the attraction between unlike monomers, an adsorption transition at some critical value is found, where the B-chain is bound to the brush-solvent interface, similar to the adsorption on a planar solid substrate. However, when is much higher than , the long macromolecule is gradually “sucked in” the brush, developing many pieces that are locally stretched in the z-direction perpendicular to the substrate, in order to fit between the brush chains. The resulting hairpin-like structures of the absorbed chain shows up via oscillatory decay of the bond vector autocorrelation function. Chain relaxation is only possible via reptation.