Correlating hydrophobicity to surface chemistry of microstructured aluminium surfaces

• Published in: Applied surface science 2021-03, Vol.542, p.148574, Article 148574
• Main Authors: Savio, L., Bhavitha, K.B., Bracco, G., Luciano, G., Cavallo, D., Paolini, G., Passaglia, S., Carraro, G., Vattuone, L., Masini, R., Smerieri, M.
• Format: Article
• Language: English
• Subjects: Aluminium alloy; Contact angle; Hydrophobicity; SEM; XPS
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2020.148574

[Display omitted] •Hydrophobicity and microscopic characteristics of Al 6060 alloys are correlated.•Hydrophobicity depends both on microstructure and surface composition.•It anticorrelates with the amount of metallic Al but carbon at the surface is essential. Highly hydrophobic aluminium surfaces fabricated by chemical etching are investigated by Contact Angle Goniometry, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy in order to correlate the wettability of our samples with their morphology at the sub-micrometer scale and with the chemical composition of the very first surface layers. We find that the etched aluminium surfaces have binary structures with nanoscale block-like convexities and hollows, which provide more space for air trapping. We also demonstrate that both hierarchical micro/nanostructures and surface composition endow these surfaces with excellent hydrophobic properties. XPS analysis shows indeed that the contact angle anti-correlates with the amount of metallic aluminium present at the surface, but also confirms the essential role of the adsorption of airborne carbon compounds. The hydrophobic behaviour depends therefore on the combined effects of surface morphology and surface chemistry.