Hydrophobicity

What is hydrophobicity? 

Hydrophobic means ‘water-fearing’. A surface is considered hydrophobic if a droplet of water creates a contact angle greater than 90°. If the contact angle is less than 90°, the surface is considered hydrophilic, ‘water-loving’. 

What is this? 

Here are two slides: one that’s normal and one that has a layer of wax on top of it. 

What does the wax do? 

Applying wax to the slide’s surface makes it hydrophobic, meaning that the surface now repels water. 

Look at how the water travels down each slide. What difference does the wax make to the water’s speed? 

Why is this important? 

A key feature of the MOF’s pores is their hydrophobicity. This means a lot of energy in the form of pressure is needed to get the water molecules inside the pores. This energy can be recovered when the pressure is removed. 

Did you know? 

There are hydrophobic surfaces that exist in nature, such as the lotus leaf. See how water moves across it! 

Our group is investigating the use of MOFs as reusable energy absorbers.