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Ion and solvent exchange processes in PGA/PAH polyelectrolyte multilayers containing ferrocyanide


Zahn, R; Boulmedais, F; Vörös, J; Schaaf, P; Zambelli, T (2010). Ion and solvent exchange processes in PGA/PAH polyelectrolyte multilayers containing ferrocyanide. Journal of Physical Chemistry. B, 114(11):3759-3768.

Abstract

We investigated ion exchange processes in poly(L-glutamic acid)/poly(allylamine)hydrochloride (PGA/PAH) polyelectrolyte multilayers containing ferrocyanide using electrochemical quartz crystal microbalance and infrared spectroscopy in attenuated total reflection. Oxidation/reduction of the ferrocyanide caused a reversible swelling of the film. We showed that the electrochemical swelling of this multilayer system depends on the ionic properties of the contacting buffer. A model was developed to explain the influence of ionic strength, the pH value, and the charge of the counterions in the buffer on the swelling behavior, by relating the swelling of the multilayer to the exchange of counterions and water molecules between the buffer and the multilayer. Changing the salts in the buffer, while maintaining the same ionic strength, showed that the swelling of the multilayer is related to the counterions' molecular mass, hydration properties, and binding strength to PAH. The hydration efficiency of different monovalent anions follows the Hofmeister series, decreasing from kosmotropic ions to chaotropic ones. In contrast, the strong binding affinity of divalent anions causes them to diverge from the Hofmeister series and to release ferrocyanide from the multilayer.

We investigated ion exchange processes in poly(L-glutamic acid)/poly(allylamine)hydrochloride (PGA/PAH) polyelectrolyte multilayers containing ferrocyanide using electrochemical quartz crystal microbalance and infrared spectroscopy in attenuated total reflection. Oxidation/reduction of the ferrocyanide caused a reversible swelling of the film. We showed that the electrochemical swelling of this multilayer system depends on the ionic properties of the contacting buffer. A model was developed to explain the influence of ionic strength, the pH value, and the charge of the counterions in the buffer on the swelling behavior, by relating the swelling of the multilayer to the exchange of counterions and water molecules between the buffer and the multilayer. Changing the salts in the buffer, while maintaining the same ionic strength, showed that the swelling of the multilayer is related to the counterions' molecular mass, hydration properties, and binding strength to PAH. The hydration efficiency of different monovalent anions follows the Hofmeister series, decreasing from kosmotropic ions to chaotropic ones. In contrast, the strong binding affinity of divalent anions causes them to diverge from the Hofmeister series and to release ferrocyanide from the multilayer.

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24 citations in Web of Science®
25 citations in Scopus®
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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:04 Faculty of Medicine > Institute of Biomedical Engineering
Dewey Decimal Classification:170 Ethics
610 Medicine & health
Language:English
Date:2010
Deposited On:26 Jan 2011 13:05
Last Modified:05 Apr 2016 14:39
Publisher:American Chemical Society
ISSN:1520-5207
Publisher DOI:https://doi.org/10.1021/jp9106074
PubMed ID:20184302

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