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Roughness in surface force measurements: Extension of DLVO theory To describe the forces between Hafnia surfaces

Eom, N., Parsons, D.F.ORCID: 0000-0002-3956-6031 and Craig, V.S.J. (2017) Roughness in surface force measurements: Extension of DLVO theory To describe the forces between Hafnia surfaces. The Journal of Physical Chemistry B, 121 (26). pp. 6442-6453.

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The interaction between colloidal particles is commonly viewed through the lens of DLVO theory, whereby the interaction is described as the sum of the electrostatic and dispersion forces. For similar materials acting across a medium at pH values remote from the isoelectric point the theory typically involves an electrostatic repulsion that is overcome by dispersion forces at very small separations. However, the dominance of the dispersion forces at short separations is generally not seen in force measurements, with the exception of the interaction between mica surfaces. The discrepancy for silica surfaces has been attributed to hydration forces, but this does not explain the situation for titania surfaces where the dispersion forces are very much larger. Here, the interaction forces between very smooth hafnia surfaces have been measured using the colloid probe technique and the forces evaluated within the DLVO framework, including both hydration forces and the influence of roughness. The measured forces across a wide range of pH at different salt concentrations are well described with a single parameter for the surface roughness. These findings show that even small degrees of surface roughness significantly alter the form of the interaction force and therefore indicate that surface roughness needs to be included in the evaluation of surface forces between all surfaces that are not ideally smooth.

Item Type: Journal Article
Murdoch Affiliation(s): School of Engineering and Information Technology
Publisher: American Chemical Society
Copyright: © 2017 American Chemical Society
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