Hello scientific comunity. Does anyone know if there is a relationship between water contact angle and membrane configuration (dense, porous, and asymmetric)? Does the water contact angle suffer changes (increase or decrease) keeping the same material and membrane shaping but changing membrane configuration from dense, to porous or asymmetrical, which one can I expect more hydrophilicity or hydrophobicity? Porosity increase of my material would affect the water contact angle of the structure?
Angelo Silva Porosity or roughness of the surface can affect hydrophilicity/hydrophobicity or water contact angle. According to Wenzel model for a given chemical composition, increase in roughness of a surface will render it more hydrophobic or more hydrophilic.
Dear Angelo Silva
Please see the following links:
Article Effect of pore morphology and surface roughness on wettabili...
Article Review of Several Experimental Methods for Characterization ...
https://www.nature.com/articles/s41598-018-34146-8
Dear all, since it is a membrane, i.e., transport properties are more concerned, I think surface free energy (surface tension) as a function of porosity and pores sizes are more inficatives. Contact angle is an indication only of the surface free energy which has nothing to do with the bulk properties of the membrane. My Regards
Dear Angelo Silva
Morphology has a significant role in terms of contact angle measurement. If the pores are more or of micro-size then there can be a lesser water contact angle in comparison to the surface having fewer pores or nano-sized. Hydrophobicity varies from material to material. Please follow the below mentioned papers
Article Thickness dependent wetting properties and surface free ener...
Article Microstructure, wettability, optical and electrical properti...
Dear Angelo Silva,
There is a strong relationship between surface pore size and roughness with the contact angle value of each material whether it is a metal or polymeric film, etc. Indeed, being a dense (non-porous) or porous surface highly affects the contact angle value because water drop can penetrate into the big pores of the surface due to the capillary forces within the pores and accordingly spread on the surface leading to a contact angle reduction.
In general, numerous factors can affect the contact angle value.
To know more, please refer to:
1. Keurentjes, J. T. F., Harbrecht, J. G., Brinkman, D., Hanemaaijer, J. H., Stuart, M. C., & Van't Riet, K. (1989). Hydrophobicity measurements of microfiltration and ultrafiltration membranes. Journal of membrane science, 47(3), 333-344.
2. Amirilargani, M., Saljoughi, E., Mohammadi, T., & Moghbeli, M. R. (2010). Effects of coagulation bath temperature and polyvinylpyrrolidone content on flat sheet asymmetric polyethersulfone membranes. Polymer Engineering & Science, 50(5), 885-893.
This new article also properly explain the influential factors:
Krainer, S., & Hirn, U. (2021). Contact angle measurement on porous substrates: Effect of liquid absorption and drop size. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 619, 126503.
Hope you the best
Foroogh
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