Comments on: Hydrophilic vs. hydrophobic. The meaning of contact angle

By: Editor

Editor — Wed, 06 May 2009 14:24:05 +0000

Dear friend,

thank you for your question. Unfortunately there is no way to connect the roughness r
of Wenzel’s equation with the roughness (ra or r rms) estimated rom a tip profilometer.
You must use an optical profilometer or even better an AFM to measure the roughness
on the surface of ZnO nanomaterials.
The above instruments have the appropriate software and estimate the ratio of the rough surface to the smooth surface which is the roughness r of the Wenzel’s equation.

Best regards,

By: kishor

kishor — Sat, 02 May 2009 12:43:09 +0000

I am working on chemical synthesis of ZnO nanomaterials. I have studied contact angle for my samples(as-deposited and annealed). The surface morphology istudy shows flakelike morphology with no any morphological changes after annealing. The contact angle decreses due to annealing probably due to increase roughness in the sample.
The contact angle decrases for increasing the surface roughness..It is in accordance with wenzals law..But for practical evidence we measure roughness on surace profiler which gives roughness in Angston unit and theorotical we use quantity “r” as roughness factor in the equation ..
The question is what is the relationship between the roughness and the roughness factor…
Plz do reply
yours sincerely

By: SuperHydroPhobicCoating.com

SuperHydroPhobicCoating.com — Sat, 04 Apr 2009 13:18:30 +0000

Thank you, Mr. Trato!
We are happy that you like our articles on the issue and we hope that you will find the time to subscribe to our news feed and participate in the discussions.

By: James Trato

James Trato — Fri, 03 Apr 2009 18:02:26 +0000

Your site has good and revelant information on hydrophobic surfaces. Have been in this field since the middle 80’s with ENVICOAT.

J. Trato