Issue 18, 2017

A self-consistent mean-field model for polyelectrolyte gels

Abstract

We present a novel approach to modeling polyelectrolyte gels, exploiting the analogy between star-branched polymers and polymer networks as a computationally inexpensive yet reliable alternative to full-scale simulations. In the numerical mean-field model of a star-like polymer we modify the boundary conditions to represent an infinite network. We validate the predictions of our new model against a coarse-grained simulation model. We also validate it against a phenomenological analytical model which has been previously shown to agree with simulations in a limited range of parameters. The mean-field model explicitly considers local density gradients and agrees with the simulation results in a broad range of parameters, beyond that of the analytical model. Finally, we use the mean-field model for predictions of the swelling behaviour of weak polyelectrolyte gels under different pH conditions. We demonstrate that the local density gradients are important and that the ionization of the weak polyelectrolyte gel is significantly suppressed. Under the studied conditions the effective pKA is about one unit higher than that of the free monomer. This shift in the effective pKA stems from the different pH values inside and outside the gel.

Graphical abstract: A self-consistent mean-field model for polyelectrolyte gels

Supplementary files

Article information

Article type
Paper
Submitted
19 Dec 2016
Accepted
11 Feb 2017
First published
13 Feb 2017
This article is Open Access
Creative Commons BY-NC license

Soft Matter, 2017,13, 3264-3274

A self-consistent mean-field model for polyelectrolyte gels

O. Rud, T. Richter, O. Borisov, C. Holm and P. Košovan, Soft Matter, 2017, 13, 3264 DOI: 10.1039/C6SM02825J

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