Complex molecules from crude oil, such as asphaltenes, can adsorb onto oil/water interfaces. This creates a viscoelastic network that may cause difficulties in oil recovery and oil spills. In addition to stabilization of oil/water emulsions, they may also cause the spontaneous formation of micron-sized droplets. Here, we investigate spontaneous emulsification in the presence of asphaltenes, probing parameters that may affect this phenomenon by observing isolated drops of water immersed in asphaltene/hydrocarbon solutions within a co-flow microfluidic device. The results indicate that the initial internal pressure of the drop strongly influences the rate at which the drop will shrink due to spontaneous emulsification. In addition, the viscoelastic skin formation by the asphaltenes inhibits increases in this pressure that normally accompanies a decrease in drop radius. Understanding this spontaneous emulsification has implications not only for the oil industry, but also to the cosmetics, foods, medical, and pharmaceutical industries.
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