Oxygen plasma is well-known to improve hydrophilicity of different materials. However, I read many scientific papers that used oxygen plasma to increase the surface nano/micro roughness, which helps to improve the contact angle after a plasma deposition.
For example: Oxygen plasma followed by a fluorocarbon coating (by plasma) resulted in a superhydrophobic surface.
My question is:
Can the effect of improvement of hydrophilicity superimposes the effect of roughness? It means, the oxygen plasma hinder the following thin film deposition instead to help creating a superhydrophobic surface.
Anyone can help me?
Kind regards,
Oxygen plasmas are known to be extremely reactive and are used to remove most kind of organic films as well as leading to surface functionalization (dangling, hydrophilic OH groups for example) It will of help to know what is exactly what you want to achieve...
Thanks Dr. Tabares. I appreciate your answer.
In fact, I'm trying to use the ability of oxygen plasma (in a DBD device) to improve the surface roughness and then, consequently, to improve the contact angle of wood through the deposition of fluorocarbon thin films in the same atmospheric pressure reactor. I'm waiting for the XPS results but my hypothesis is based on the level of contamination and oxygen moieties in the environment are enough to mask the effect of roughness in the contact angle, prevailing the effect of O moieties attached to the surface.
The most of the papers that I read about the use of oxygen plasma (to improve nano/micro roughness) + fluorocarbon coating by plasma were performed in low-pressure reactors.
I expect successful etching and increasing of wettability and roughness of wood surface during first stage (oxygen plasma treatment). Then you want to use fluorocarbon containing gas to eliminate wettability and increase water contact angle. Here the problem starts. It is possible but I expect problem because of atmospheric pressure reactor. Residual moisture will split to hydroxyl group and hydrogen, certain amount of hydrogen will bond to florine and fly off and it could decrease the efficiency rapidly. That's the reason, why this treatment is mostly made in vaccum systems with strong pumps as you read. Lower base pressure better. The wood could hold residual water also.
Thank you very much Dr. Grulich. Your answer was very useful and it makes sense. I'm waiting the XPS results to confirm this hypothesis.
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