I am measuring water contact angle on the surface of a polymeric composite which has the roughness factor of the order of 1-2 micrometer. I would like to confirm the state of water droplet on this hydrophobic surface (either Wenzel or Cassie state). The instrument which we have permits only tilt method for measuring Advancing and receding contact angles. However, the water drop does not roll off from the sample surface even after tilting if by 90 degree. The contact angle on the upper lower side of the droplet shows an irregular trend while tilting. Is it possible to distinguish Cassie or Wenzel state from the data I have?
Yes is possible, with Optical Microscopy.
The bright/dark contrast between the Wenzel and Cassie-Baxter
states is attributed to the difference in refractive index of
water and air in the grooves. Furthermore, coexisting
Wenzel and Cassie-Baxter states.
Yes. Definitely Wenzel state. You have a huge CA-hysteresis. I am convinced that both espesially the uphill angle is strongly pinned. Concerning your irregular trend you may compare with our results. I guess that additionally your software results in some errors during the CA determination. You may also be able to increase the volume.
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