Скачать или смотреть Superhydrophobic surface: lycopodium spores

Lycopodium spores have unique superhydrophobic properties. In this video, we demonstrate and explain an experiment where spores floating on water create an effect that keeps a leaf dry when it touches the water.

1. Fill a glass with water.
2. Spread lycopodium spores on the water surface in a 1mm layer.
3. Put a leaf into the water (through the layer of lycopodium spores).

Lycopodium (Lycopodium clavatum) is a member of the club mosses family and is a spore plant. Lycopodium spores are very small particles, with an average diameter of 30 microns.

Spores have poor wettability, that’s why they do not sink in water.
Lycopodium spores form a protective (hydrophobic) layer between the leaf and water, therefore the leaf stays dry after being immersed in water.

Hydrophobicity is a property of substances or material not to mix and interact with water. We call the materials hydrophobic when the contact angle between the surface and a water drop on it is more than 90 degrees.

The contact angle is the angle between a liquid surface and a solid surface where they meet. The more contact angle is, the less wettability is.

Superhydrophobic surfaces are those whose contact angles of a water droplet exceeds 150°. Lycopodium spores exhibit superhydrophobicity.

Interesting fact: lycopodium spores are used in the pyrotechnics production of and in forensics (to identify fingerprints). Earlier the pharmacists used the spores to dry out the wounds.

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