Hydrophobic pore array surfaces: Wetting and interaction forces in water/ethanol mixtures

Petra M. Hansson, Yashar Hormozan, Birgit D. Brandner, Jan Linnros, Per Claesson, Agne Swerin, Joachim Schoelkopf, Patrick A.C. Gane, Esben Thormann

Research output: Contribution to journalJournal articleResearchpeer-review


Interactions between and wetting behavior of structured hydrophobic surfaces using different concentrations of water/ethanol mixtures have been investigated. Silica surfaces consisting of pore arrays with different pore spacings and pore depths were made hydrophobic by silanization. Their static and dynamic contact angles were found to be independent of the pore depth while fewer pores on the surface, i.e. a closer resemblance to a flat surface, gave a lower contact angle. As expected, a higher amount of ethanol facilitated wetting on all the surfaces tested. Confocal Raman microscopy measurements proved both water and ethanol to penetrate into the pores. AFM colloidal probe force measurements clearly showed that formation of air cavitation was hindered between the hydrophobic surfaces in presence of ethanol, and an increase in ethanol concentration was followed by a smaller jump-in distance and a weaker adhesion force. On separation, an immediate jump-out of contact occurred. The measured forces were interpreted as being due to capillary condensation of ethanol between the surfaces giving rise to very unstable cavities immediately rupturing on surface separation.
Original languageEnglish
JournalJournal of Colloid and Interface Science
Pages (from-to)278-286
Publication statusPublished - 2013
Externally publishedYes


  • Surface force
  • AFM
  • Capillary condensation
  • Ethanol
  • Pore array surfaces
  • Hydrophobic interaction
  • Wetting

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