Chain expulsion out of dense polymer brushes

Abstract

Langevin dynamics simulations are used to study the expulsion of single chains out of dense polymer brushes in a good solvent. The dynamic scaling model is able to correctly predict certain features of the expulsion process, but it fails to describe details of the time-resolved dynamics of monomers. The center of mass velocity of the moving chain is not strictly constant but accelerating during the expulsion process. The driving force of the expulsion process, the (negative) vertical gradient of the brush density profile, undergoes a qualitative change when the brush profile is transformed from a parabolic to a box-like profile at high densities. © 2008 WILEY-VCH Verlag GmbH & Co. KGaA.