Hydrophobic materials repel water, but why?Well water is an interesting thing and has a tendency to react with most things it touches, either in dissolving the material or chemically reacting. Hydrophobic materials buck this trend, they cannot interact with water and as a result the water will move very freely across the material. A large number of materials are hydrophobic your skin is one of them. Though one of the of the most prevalent ones is wax as it can be spread on any surface to improve it’s hydrophobic abilities.
Wax stops water reacting with surfaces which also reduces the ability of water to grip to any surface improving drying time and causing the beading effect you see here.
However they are some superhydrophic materials and they are actually quite insane to watch in action, Super or Ultrahydrophobic materials are extremely hard to wet and you can see a video of the water reacting to the different surfaces in the video below.
Some common misconceptions to deal with is that hydrophobic surfaces do not give water energy when they repel it. It just makes the surface have a very low coefficient of friction meaning the water cannot grip the material (for this reason it is popular in swim suits). Hydrophobic is often referred to as ‘unwettable’ this is true to an extent but dipping an item coated in a hydrophobic material doesn not amke it force water away from itself it merely stops the water interacting with the object.