Eur. Phys. J. E 6, 37-47 (2001)

Adsorption of hydrophobic polyelectrolytes onto oppositely charged surfaces

O.V. Borisov¹, F. Hakem^{2, 3}, T.A. Vilgis^{3, 4}, J.-F. Joanny⁴ and A. Johner<sup>3, 4

1</sup>  LRMP/UMR 5067, Hélioparc Pau-Pyrénées, 64053 Pau, France
²  University Aboubakr Belkaid, Faculty of Sciences, Department of Physics, BP 119, Tlemcen 13 000, Algeria
³  LEA (MPIP, ICS) Max Planck Institut für Polymerforschung, Ackermann weg 2, 55128, Mainz, Germany
⁴  Institut Charles Sadron, 6 rue Boussingault, 67083, Strasbourg, France

johner@ics.u-strasbg.fr

(Received 12 April 2001)

Abstract
We present a scaling theory for the adsorption of a weakly charged polyelectrolyte chain in a poor solvent onto an oppositely charged surface. Depending on the fraction of charged monomers and on the solvent quality for uncharged monomers, the globule in the bulk of the solution has either a spherical conformation or a necklace structure. At sufficiently high surface charge density, a chain in the globular conformation adsorbs in a flat pancake conformation due to the Coulombic attraction to the oppositely charged surface. Different adsorption regimes are predicted depending on two screening lengths (the Debye screening length monitored by the salt concentration and the Gouy-Chapman length monitored by the surface charge density), on the degree of ionization of the polymer and on the solvent strength. At low bulk ionic strength, an increase in the surface charge density may induce a transition from an adsorbed necklace structure to a uniform pancake due to the enhanced screening of the intra-chain Coulombic repulsion by the counterions localized near the surface.

PACS
36.20.Ey - Conformation (statistics and dynamics).
82.35.Gh - Polymers on surfaces; adhesion.
61.30.Hn - Surface phenomena: alignment, anchoring, anchoring transitions, surface-induced layering, surface-induced ordering, wetting, prewetting transitions, and wetting transitions.


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