Motion

by Dana Plesa

I thought, wouldn’t it be cool to create my own imaginary galaxy?

A galaxy, like the Milky Way, is a dynamic interstellar cloud ruled by the laws of physics and chemistry.

For the creation of my little piece of the universe, all mighty me chose a “smart” class of substances that I have always loved, called surfactants. Why do I consider them “smart”, you ask?

A surfactant is a molecule that consists of two parts: the “head”, which is polar (it has an affinity for water), and the “tail” that is non-polar (it has an affinity for oil). Laundry detergents are examples of surfactants. Because of this dual affinity (to both water and oil), surfactants can spontaneously re-orient or self-assemble in solution to form structures named micelles. That is why detergents clean; in water the surfactant aggregates to form spherical micelles with the heads aligned along the outside and the tails pointing inside, thus trapping the dirt (which is usually “oily”) inside the sphere.

In this collection, a droplet of surfactant (fluorescent green under UV light) spreads beautifully on top of a polar solution (like alcohol) to form swirls when the molecules come in contact with the alcohol and change their orientation, so the polar “head” is in contact with the alcohol.

When the surfactant spreads in thin layer on a non-polar solution, and interacts with a polar solution (like alcohol), a very strong convective motion is produced.

So, here it is my own micro-galaxy.