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Soft Matter and Biological Physics


Eur. Phys. J. E 6, 377-386 (2001)

Complexation between oppositely charged polyelectrolytes: Beyond the Random Phase Approximation

M. Castelnovo and J.-F. Joanny

Institut Charles Sadron (CNRS UPR 022), 6 rue Boussingault, 67083 Strasbourg Cedex, France

castel@ics.u-strasbg.fr

(Received 16 January 2001)

Abstract
We consider the phase behavior of polymeric systems by calculating the structure factors beyond the Random Phase Approximation. The effect of this correction to the mean-field RPA structure factor is shown to be important in the case of Coulombic systems. Two examples are given: simple electrolytes and mixtures of incompatible oppositely charged polyelectrolytes. In this last case, all former studies predicted an enhancement of compatibility for increasing charge densities; we also describe the complexation transition between the polyelectrolytes. We determine a phase diagram of the polyelectrolyte mixture that includes both complexation and incompatibility.

PACS
82.35.Rs - Polyelectrolytes.
82.35.Jk - Copolymers, phase transitions, structures.
64.70.Nd - Structural transitions in nanoscale materials.


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