Superhydrophobic surfaces are gaining more and more attention as new applications for them arises. For surface to be superhydrophobic, it has to fulfil two requirements. The static contact angle has to be over 150 degrees but in addition to that, the surface has to have a low contact angle hysteresis. For this reason, measurement of dynamic contact angles is especially important when superhydrophobic surfaces are studied.
There are two main methods for dynamic contact angle measurement; tilting cradle and a so-called needle method. Tilting cradle is fairly often used for dynamic contact angle measurements but can be troublesome for superhydrophobic surfaces. Placing the drop on superhydrophobic surface is somewhat difficult as the drop would prefer to stay in the needle. Also the drop rolls off the image very easily as the contact angle hysteresis is low. For these reasons most of the people prefer the needle method where needle is left in contact with the drop.
Watch the short webinar through the link below to see how contact angle measurements can be done in practice on superhydrophobic surfaces.
The earliest known reference to contact angle measurement was made by Thomas Young in 1805.
Chemical etching of fluoropolymers is a process used to selectively remove material from the surface using chemical solutions to improve wettability.
This difference in wettability is key in determining how each membrane is used.
Drop volume can have an effect on contact angles on certain surfaces.
Advancing contact angle is the highest possible contact angle measured on a previously unwetted solid surface.
Roughness corrected contact angle, is an angle where the effect of surface roughness is taken away.
Instead, one can measure static contact angles, advancing and receding contact angles, and roughness corrected contact angles.
For the mechanical performance of the composite, the adhesion between fiber and the matrix is of utmost importance.
Hydrophobic coatings are used in many consumers products. Contact angle measurements can be used to study them.