Issue 22, 2017

Local pH and effective pKA of weak polyelectrolytes – insights from computer simulations

Abstract

In this work we study the titration behavior of weak polyelectrolytes by computer simulations. We analyze the local pH near the chains at various conditions and provide molecular-level insight which complements the recent experimental determination of this quantity. Next, we analyze the non-ideal titration behaviour of weak polyelectrolytes in solution, calculate the effective ionization constant and compare the simulation results with theoretical predictions. In contrast with the universal behaviour with respect to chain length, we find non-universality and deviations from theory with respect to polymer concentration and permittivity of the solvent. The latter we explain in terms of counterion condensation and ion correlation effects, which lead to reversal of the non-ideal titration behaviour at very low permittivities. We discuss the impact of these findings on the interpretation of experimental results.

Graphical abstract: Local pH and effective pKA of weak polyelectrolytes – insights from computer simulations

Supplementary files

Article information

Article type
Paper
Submitted
13 Jan 2017
Accepted
28 Feb 2017
First published
28 Feb 2017
This article is Open Access
Creative Commons BY-NC license

Phys. Chem. Chem. Phys., 2017,19, 14376-14387

Local pH and effective pKA of weak polyelectrolytes – insights from computer simulations

L. Nová, F. Uhlík and P. Košovan, Phys. Chem. Chem. Phys., 2017, 19, 14376 DOI: 10.1039/C7CP00265C

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