Pickering Emulsions and Equilibrium Time: Kinetic Study

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Processes of emulsion destabilzation: A) creaming B) sedimentation C)phase inversion d) floculation E) Coalescence F) Oswald maturing: Image by Onegumas

Emulsions: Reaching Equilibrium Conditions

In the experiment, the water-oil interface was monitored with time. A weak laser radiation was used to “push” the particle towards the fluid interface and breach it. After the breach, the particle straddled between the two fluids, as expected. What was not expected, however, was the timescale necessary for the system to reach the equilibrium conditions: this stage took much longer than predicted.

Data showed that the system evolved at a very slow pace, and it did not reach equilibrium in the timescale of the experiment (tens of seconds).

The time necessary to achieve such conditions was extrapolated using a mathematical model based on a logarithmic behavior; this predicted that months may be necessary to achieve equilibrium.

Emulsion Equilibrium: Surprising Results

Professor Manoharam explained to Decoded Science: “These results were quite surprising and exciting, as we did not expect the system to take so long to reach equilibrium. The data showed that the kinetic modeling of Pickering emulsions needs further investigation. This kind of emulsion has many practical applications, for fields such as medicine (i.e. drug delivery) or in the manufacturing of nanomaterials. Therefore, it is important to understand exactly the timescale of the process.”

Importance of Emulsion Stability

The stability of emulsions, or the length of time before an emulsion separates into its original elements, depends on a number of factors. Now that researchers have found that Pickering emulsions, or which are stabilized by the addition of small particles of a solid, are extremely stable. This discovery may have implications in the medical sciences, as well as in other areas, such as the food industry.

Resources

Jeong, T. H. Basic Principles and Applications of Holography. Accessed January 16, 2012.

Kaz, D. M., et al. Physical ageing of the contact line on colloidal particles at liquid interfaces Nature Materials. Doi:10.1038/nmat3190 (2011). Accessed January 16, 2012.

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