Quantification of the structure of colloidal shared-solvent fluid–fluid interfaces

ESRF-ILL Soft Matter Colloquium
Start Date
16-01-2020 15:00
End Date
16-01-2020 16:00
Science Building Seminar Room 036
Speaker's name
Mark VIS
Speaker's institute
Eindhoven University of Technology & ENS Lyon
Contact name
Eva Jahn
Host name
Diego Pontoni, Yuri Gerelli
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We have quantified experimentally the width and structure of the colloidal gas–liquid interface. Our model system comprises spherical colloids that are sterically stabilized in an apolar solvent. Colloidal gas–liquid phase-separation is induced through the depletion interaction, i.e., by addition of nonadsorbing polymer. The broadness of the resulting colloidal gas–liquid interface was probed using synchrotron X-ray reflectivity measurements at various points in the phase diagram. We find that the interfacial width is comparable to the size of the colloidal particles and that it scales in a meanfield fashion with the density difference. Our results further suggest that the density profiles are monotonic. The experimental results show excellent agreement with theoretical predictions based on free-volume theory and highlight that X-ray reflectivity experiments can be used to shed light on the intricate structure of these colloidal interfaces.

M. Vis1,2,3, J.H. Brouwer1,2,4, A. González García4,1,2, A.V. Petukhov4,1, O. Konovalov5, R. Tuinier1,2,4

1 Laboratory of Physical Chemistry, Eindhoven University of Technology, The Netherlands 2 Institute for Complex Molecular Systems, Eindhoven University of Technology, The Netherlands 3 Laboratoire de Chimie, ENS de Lyon, France 4 Van ’t Hoff laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, The Netherlands 5 European Synchrotron Radiation Facility, Grenoble, France

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