Video: Surface science keeps liquids rolling off superhydrophobic materials | The American Ceramic Society

Video: Surface science keeps liquids rolling off superhydrophobic materials

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[Image above] Credit: Reactions; YouTube

I’ve said it before, and I’ll say it again—surfaces are critically important because they influence how a material interacts with the rest of the world.

In fact, governing a material’s surface properties—which some say is best done through a combination of engineered nanostructure and surface coatings—can drastically change that material’s functionality.

Such engineering has given us glass that is antiglare, antireflective, and superhydrophobic (“water-fearing”)—making the material seem so clear that it is barely visible.

It’s also given us superior surfaces that are not just superhydrophobic, but so incredibly durable that they can stand up to some serious abuse.

And, in our everyday lives, such engineering allows our raincoats, windshields, and phones to repel water and remain functional even when the weather doesn’t cooperate.

So we can definitely engineer some pretty incredible surfaces—but what is it that makes water roll right off?

Taking inspiration from superhydrophobic materials found in nature, such as the surfaces of lotus leaves and wings of the leafhopper bug, scientists know that it all comes down to the ever-important contact angle. That’s the angle formed at the contact point between a drop of liquid sitting on the surface and the surface itself.

A higher contact angle means that the drop is sitting further up off the surface, better maintaining its spherical shape. That equates to a surface being more superhydrophobic because that drop can keep on rolling, right off of the surface.

It’s the reason why superhydrophobic surfaces—whether a ceramic, polymer, or a T-shirt—stay dry in the face of a liquid assault.

Watch this short ACS Reactions video to learn more about this super surface science.

Credit: Reactions; YouTube