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Attractive non-DLVO forces induced by adsorption of monovalent organic ions

Published inPhysical Chemistry Chemical Physics, vol. 20, no. 1, p. 158-164
Publication date2018
Abstract

Direct force measurements between negatively charged colloidal particles were carried out using anatomic force microscope (AFM) in aqueous solutions containing monovalent organic cations, namely tetraphenylarsonium (Ph4As+), 1-hexyl-3-methylimidazolium (HMIM+), and 1-octyl-3-methylimidazolium(OMIM+). These ions adsorb to the particle surface, and induce a charge reversal. The forces become attractive at the charge neutralization point, but they are stronger than van der Waals forces. This additional and unexpected attraction decays exponentially with a decay length of a few nanometers, andis strikingly similar to the one previously observed in the presence of multivalent ions. This attractive force probably originates from coupled spontaneous charge fluctuations on the respective surfaces as initially suggested by Kirkwood and Shumaker.

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Citation (ISO format)
SMITH, Alexander, MARONI, Plinio, BORKOVEC, Michal. Attractive non-DLVO forces induced by adsorption of monovalent organic ions. In: Physical Chemistry Chemical Physics, 2018, vol. 20, n° 1, p. 158–164. doi: 10.1039/C7CP06383K
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ISSN of the journal1463-9076
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