Issue 17, 2011

Attractive interactions between colloids at the oil–water interface

Abstract

The effects of salts and surfactants on the interaction force between colloidal polystyrene latex particles confined to a decane–water interface are measured directly using optical tweezers. After adding 0.25 M NaCl, 0.25 M NaCl and 0.1 mM sodium dodecyl sulfate (SDS) to the aqueous sub-phase, or 25 μM sorbitan monooleate (SPAN 80) to the decane super-phase, the strong repulsive force between particles is reduced and an attractive force becomes significant. The magnitude and dependence of the attraction on particle separation is consistent with a capillary quadrupole interaction. Similar interaction forces between polystyrene latex doublet particles at a pristine interface are measured, however, the anisotropic particles exhibit only a long-range attraction that is approximately two orders of magnitude stronger than spherical colloids. These results confirm the presence of long-range capillary attractions and provide a guide for manipulating colloidal interactions with additives or particle shape at fluid interfaces to control suspension structure and surface rheology.

Graphical abstract: Attractive interactions between colloids at the oil–water interface

Supplementary files

Article information

Article type
Paper
Submitted
04 Січ 2011
Accepted
22 Бер 2011
First published
26 Кві 2011

Soft Matter, 2011,7, 7676-7682

Attractive interactions between colloids at the oil–water interface

B. J. Park and E. M. Furst, Soft Matter, 2011, 7, 7676 DOI: 10.1039/C1SM00005E

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