Jump to main content
Jump to site search

Issue 21, 2014
Previous Article Next Article

Unconventional ordering behavior of semi-flexible polymers in dense brushes under compression

Author affiliations

Abstract

Using a coarse-grained bead-spring model for semi-flexible macromolecules which form a polymer brush, the structure and dynamics of the polymers were investigated, varying the chain stiffness and the grafting density. The anchoring conditions for the grafted chains were chosen such that their first bonds were oriented along the normal to the substrate plane. The compression of such a semi-flexible brush by a planar piston was observed to be a two-stage process: for a small compression the chains were shown to contract by “buckling” deformation whereas for a larger compression the chains exhibited a collective (almost uniform) bending deformation. Thus, the stiff polymer brush underwent a 2nd order phase transition of collective bond reorientation. The pressure, required to keep the stiff brush at a given degree of compression, was thereby significantly smaller than for an otherwise identical brush made of entirely flexible polymer chains! While both the brush height and the chain linear dimensions in the z-direction perpendicular to the substrate increased monotonically with an increase in the chain stiffness, the lateral (xy) chain linear dimensions exhibited a maximum at an intermediate chain stiffness. Increasing the grafting density led to a strong decrease of these lateral dimensions which is compatible with an exponential decay. Also the recovery kinetics after removal of the compressing piston were studied, and were found to follow a power-law/exponential decay with time. A simple mean-field theoretical consideration, accounting for the buckling/bending behavior of semi-flexible polymer brushes under compression was suggested.

Graphical abstract: Unconventional ordering behavior of semi-flexible polymers in dense brushes under compression

Back to tab navigation

Publication details

The article was received on 18 Dec 2013, accepted on 18 Feb 2014 and first published on 19 Feb 2014


Article type: Paper
DOI: 10.1039/C3SM53133C
Citation: Soft Matter, 2014,10, 3783-3797
  •   Request permissions

    Unconventional ordering behavior of semi-flexible polymers in dense brushes under compression

    A. Milchev and K. Binder, Soft Matter, 2014, 10, 3783
    DOI: 10.1039/C3SM53133C

Search articles by author

Spotlight

Advertisements