Theory of the polyelectrolyte dielectric function

• Published in: Physical review. E, Statistical, nonlinear, and soft matter physics Vol. 84; no. 4 Pt 1; p. 041804
• Main Author: Lu, C-Y David
• Format: Journal Article
• Language: English
• Published: United States 01.10.2011
• ISSN: 1550-2376
• DOI: 10.1103/PhysRevE.84.041804

A simple double-layer polarization theory is developed for the flexible polyelectrolyte solution. Under the applied electric field, the double layer of the polyelectrolyte induces the excess line fluxes of charge and salt within the double layer. The off-diagonal Onsager coefficient couples the charge and the neutral salt dynamics so that the salt distribution is perturbed by the applied electric field. The nonuniform salt then drives the excess double-layer electric current. We show that the dielectric function can be expressed as the free energy storage and loss within the electric field and the salt distribution. At the leading Born approximation, the dielectric function depends on the chain configuration through the chain structure function. We use a simple mean-field structure function to calculate the dielectric function, where a closed-form expression is obtained. A detailed prediction is made for the full range of the polyelectrolyte concentration.