Eur. Phys. J. E 10, 303-318 (2003)
DOI: 10.1140/epje/i2002-10115-0

Charge relaxation in polyampholytes of various statistics

S. Moldakarimov¹, A. Johner^{1, 2} and J.F. Joanny<sup>3

1</sup>  Institut Charles Sadron, 6 rue Boussingault, 67083 Strasbourg Cedex, France
²  Laboratoire Européen Associé (LEA) ICS/MPIP(Mainz, Germany)
³  Physicochimie Curie, Institut Curie Section Recherche, 26 rue d'Ulm, 75248 Paris, France

johner@ics.u-strasbg.fr

(Received 20 December 2002 / Published online: 24 April 2003)

Abstract
We discuss theoretically the relaxation of charge fluctuations in polyampholyte solutions. It has been shown previously by some of us (J. Wittmer et al. , Europhys. Lett. 24, 263 (1993)) that the charge distribution along the polyampholyte backbone has a dramatic influence on the polarization energy and hence on the solubility. Here it is demonstrated that a similar effect exists for the charge relaxation. The charge relaxation mechanism qualitatively depends on the statistics: for alternating polyampholytes the relaxation is mainly due to local dipole inversion and is not primarily driven by electrostatic interactions, whereas for random polyampholytes it is driven by electrostatic interactions. Intermediate statistics (with short-ranged (exponential) correlations) appear as a combination of these two limiting cases: short-wavelength modes are insensitive to the loss of correlations along the backbone, whereas long-wavelength modes correspond to a random statistics with renormalized charges. The relaxation of the dielectric constant is also calculated.

PACS
61.25.Hq - Macromolecular and polymer solutions; polymer melts; swelling.

© EDP Sciences, Società Italiana di Fisica, Springer-Verlag 2003