Eur. Phys. J. E 4, 505-513

Collapse of polyelectrolyte brushes: Scaling theory and simulations

F.S. Csajka¹, R.R. Netz¹, C. Seidel¹ and J.-F. Joanny<sup>2

1</sup>  Max-Planck-Institut für Kolloid- und Grenzflächenforschung, Am Mühlenberg, D-14476 Golm, Germany
²  Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, France

netz@mpikg-golm.mpg.de
seidel@mpikg-golm.mpg.de

(Received 26 September 2000)

Abstract
We investigate polyelectrolyte brushes using both scaling arguments and molecular dynamics simulations. As a main result, we find a novel collapsed brush phase. In this phase, the height of the brush results from a competition between steric repulsion between ions and monomers and an attractive force due to electrostatic correlations. As a result, the monomer density inside the brush is independent of the grafting density and the polymerization index. For small ionic and monomer radii (or for large Bjerrum length) the brush undergoes a first-order phase transition from the osmotic into the collapsed state.

PACS
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.
68.45.Ws - Other nonelectronic properties.
61.20.Qg - Structure of associated liquids: electrolytes, molten salts, etc..


© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2001