Mon June 27th 2016
14:00 – 15:00
Seminar Probing Surface Interaction Mechanisms of Deformable Emulsion Droplets and Air Bubbles
Hongbo Zeng


The intermolecular and surface interactions at solid/oil/water/bubble interfaces play critical roles in many industrial processes. Stable water-in-oil (W/O) and oil-in-water (O/W) emulsions are undesirable in oil production (e.g., oil/water separation process). Adsorption of asphaltenes at oil/water interface is believed to be a main stabilizing factor for these emulsions. In this talk, I will first introduce the basics of intermolecular and surface force measurements, and then report our recent progress in probing the interaction mechanisms of deformable W/O and O/W emulsion droplets and air bubbles. The intermolecular interactions of asphaltenes under different solvent conditions were first measured using a surface forces apparatus (SFA). Micropipette and in-house built 4-roll mill fluidic device were applied to monitor the stability of both pipette-supported and freely suspended emulsions in the presence of asphaltenes under quasi-static and dynamic flow conditions, respectively. The interaction forces between two O/W or W/O emulsion drops in the absence and presence of asphaltenes were directly measured using droplet probe atomic force microscopy (AFM) and analysed using a theoretical model based on Reynolds lubrication theory and augmented Young-Laplace equation by including the effects of disjoining pressure. Our results have provided new insights into the stabilization/destabilization mechanisms of W/O and O/W emulsion droplets in the presence of interfacial active materials like asphaltenes. The same methodology has been also applied to quantify the hydrophobic interaction in asymmetric system between air bubble and hydrophobic surface, showing a general interaction potential. We have provided a feasible method for synchronous measurements of the interaction forces with sub-nN resolution and the drainage dynamics of thin films down to nm thickness involving deformable air bubbles and liquid droplets.

Short bio: Prof. Hongbo Zeng received his BSc and MSc in Chemical Engineering and Polymer Materials at Tsinghua University, and obtained his PhD in Chemical Engineering at the University of California, Santa Barbara. He joined the Department of Chemical and Materials Engineering at the University of Alberta as an Assistant Professor in August 2009. His early promotion to Associate Professor (Tenured) was approved in the fall 2012, and promotion to full Professor was approved in the fall 2015. He is leading a research team of over 25 PhD/MSc graduate students and postdoctoral fellows. His research interests are in the areas of colloid and interface science, functional materials & nanotechnology, with a special focus on the intermolecular and surface interactions in different material systems and complex fluids, and development of functional materials. Prof. Zeng edited and co-authored a book “Polymer Adhesion, Friction and Lubrication” (Wiley), and has published 7 book chapters and over 120 peer-reviewed papers in related journals (e.g., PNAS, Advanced Materials, Nature Communications, Advanced Functional Materials, ACS Nano, Angewandte Chemie International Edition, Biomaterials, Macromolecules, Journal of Physical Chemistry B &C, Langmuir). He received the Petro-Canada Young Innovator Award in 2013 and the Canadian Journal of Chemical Engineering Lectureship Award in 2016.
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The 10th Complex Motion in Fluids 2021
Max Planck Gesellschaft
Centre for Scientific Computing