Probing Mechanical Properties of Water–Crude Oil Interfaces and Colloidal Interactions of Petroleum Emulsions Using Atomic Force Microscopy

Abstract

Atomic force microscopy (AFM) is frequently used to elucidate complex interactions in emulsion systems. However, comparing results obtained with “model” planar surfaces to curved emulsion interfaces often proves unreliable, because droplet curvature can affect adsorption and arrangement of surface-active species, while droplet deformation affects the net interaction force. In the current study, AFM was used to study the interactions between a colloidal probe and water droplet. Force magnitude and water droplet deformation were measured in toluene solutions of asphaltene or bitumen at different concentrations and varying droplet aging time. Interfacial stiffening and an increase in particle–droplet adhesion force were observed upon droplet aging in bitumen solution. As reported in our previous study (Kuznicki, N. P., Harbottle, D., Masliyah, J., and Xu, Z. Dynamic Interactions between a Silica Sphere and Deformable Interfaces in Organic Solvents Studied by Atomic Force Microscopy. Langmuir 2016, 32 (38), 9...