A team from Devinci Research Center, composed of Pascal Clain and Walid Samah and researchers from the Frise Lab INRAE has had a paper published in Science Direct. The title of the paper is “Experimental investigation on the wetting behavior of a superhydrophobic surface under controlled temperature and humidity”.
Superhydrophobic surfaces are extremely difficult to wet, such as lotus leaves, duck, or peacock feathers. The contact angle of a drop of water on a superhydrophobic material is greater than 150°.
New knowledge on superhydrophobic properties developed as part of a thesis at Devinci Research Center
A slight inclination – less than 10° from the horizontal – allows the drop to roll off the surface. They are of great interest in various industrial fields (anti-icing coating, self-cleaning properties, control of bacterial growth etc.). However, the application of these surfaces in cold, humid and submerged environments (as in the case of ice slurry production) sometimes presents problems related to the loss of their superhydrophobic properties.
Thus the DVRC and the Frise-Inrae team have published an experimental study to characterize the wetting behavior of a surface covered with a superhydrophobic coating at different surface temperatures and relative humidity.
This work is currently being carried out as part of the co-supervision of Walid Samah’s thesis by Pascal Clain, research associate professor at ESILV, a member of the Modeling Group at Devinci Research Center.
The results of the research published in Science Direct
In the paper published in an Elsevier International Journal devoted to the Principles and Applications of Colloid and Interface Science, the authors of the study describe three methods to characterize the wetting behavior.
The first method consists in depositing a drop of water on the cooled superhydrophobic surface. The objective is to characterize the static wetting behavior (evolution of contact angles) during the cooling of the surface for different relative humidities.
The second method consists in dropping a drop of water on the cooled surface with an impact speed of 1 m/s. This method allows to characterize the dynamic behavior of the wetting (impact and rebound of the drop) at different temperatures.
The third method, consists in studying the effect of the immersion of the surface in a volume of water cooled until supercooling then freezing.
The results of the static wetting study show that the superhydrophobic coating loses its non-wetting properties at temperatures below 13 ◦C for a relative humidity between 13% and 50% due to condensation on the surface. The results of the dynamic wetting study show that the superhydrophobic coating has poor resistance to water drop impact at the surface temperature.