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MIT scientists develop new way to mix oil and water

The top row of images shows the water droplets on an oil bath coalescing and getting bigger. The bottom row shows that when a surfactant is added to the oil bath, the droplets are more stable and remain small.
MIT researchers
The top row of images shows the water droplets on an oil bath coalescing and getting bigger. The bottom row shows that when a surfactant is added to the oil bath, the droplets are more stable and remain small.

You can mix oil and water.

In its continuing quest to upend old verities and the sayings that spring from them, MIT, which recently announced it was working on technology to see around corners, is developing a new way to make oil and water mix.

The new process could find applications in pharmaceuticals, cosmetics, and processed foods, among other areas, the university said in a statement. Imagine, for example, salad dressing that never separates.

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The process involves cooling a bath of oil containing a small amount of surfactant (a substance that reduces surface tension, e.g., soap) in a chamber with very humid air. Tiny water droplets form on the surface that sink into the oil and stay mixed for months, rather than separating in just a few minutes, the university said.

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The key to overcoming that separation is to have really small, nanoscale droplets,” graduate student Ingrid Guha explained. “When the drops are small, gravity can’t overcome them,” and they can remain suspended in the mix indefinitely.

Other processes are already available that break down the droplets by shaking or using sound waves, but those processes require more energy, the university said. The new approach is very inexpensive.

The findings, by Guha, former postdoc Sushant Anand, and associate professor Kripa Varanasi, are reported in the journal Nature Communications.