What is contact angle?
Contact angle is described as the interaction between a liguid and a solid. The angle between the surface of the liquid and the contact surface is called the contact angle θ.
With a contact angle being higher than 90°, the solid is not wettable.
In case the contact angle is lower than 90°, we can say the solid is wettable.
When the contact angle is 0°, there is a complete wetting.