Change search
ReferencesLink to record
Permanent link

Direct link
Hydrophobic pore array surfaces: Wetting and interaction forces in water/ethanol mixtures
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface and Corrosion Science.
KTH, School of Information and Communication Technology (ICT), Material Physics.
KTH, School of Information and Communication Technology (ICT), Material Physics.ORCID iD: 0000-0002-5260-5322
Show others and affiliations
2013 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 396, 278-286 p.Article in journal (Refereed) Published
Abstract [en]

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.

Place, publisher, year, edition, pages
2013. Vol. 396, 278-286 p.
Keyword [en]
Surface force, AFM, Capillary condensation, Ethanol, Pore array surfaces, Hydrophobic interaction, Wetting
National Category
Other Chemistry Topics
URN: urn:nbn:se:kth:diva-103408DOI: 10.1016/j.jcis.2013.01.040ISI: 000316372400038ScopusID: 2-s2.0-84875420239OAI: diva2:559951
Swedish Foundation for Strategic Research

QC 20130506. Updated from manuscript to article in journal.

Available from: 2012-10-11 Created: 2012-10-11 Last updated: 2013-05-06Bibliographically approved
In thesis
1. Hydrophobic surfaces: Effect of surface structure on wetting and interaction forces
Open this publication in new window or tab >>Hydrophobic surfaces: Effect of surface structure on wetting and interaction forces
2012 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The use of hydrophobic surfaces is important for many processes both in nature and industry. Interactions between hydrophobic species play a key role in industrial applications such as water-cleaning procedures and pitch control during papermaking but they also give information on how to design surfaces like hydrophobic mineral pigments.

In this thesis, the influence of surface properties on wetting and interaction forces has been studied. Surfaces with close-packed particles, pore arrays, randomly deposited nanoparticles as well as reference surfaces were prepared. The atomic force microscope (AFM) was utilized for force and friction measurements while contact angles and confocal Raman microscopy experiments were mainly used for wetting studies.

The deposition of silica particles in the size range of nano- to micrometers using the Langmuir-Blodgett (LB) technique resulted in particle coated surfaces exhibiting hexagonal close-packing and close to Wenzel state wetting after hydrophobization. Force measurements displayed long-range interaction forces assigned to be a consequence of air cavitation. Smaller roughness features provided larger forces and interaction distances interpreted as being due to fewer restrictions of capillary growth. Friction measurements proved both the surface structure and chemistry to be important for the observed forces.

On hydrophobic pore array surfaces, the three-phase contact line of water droplets avoided the pores which created a jagged interface. The influence of the pores was evident in the force curves, both in terms of the shape, in which the three-phase contact line movements around the pores could be detected, as well as the depth of the pores providing different access and amount of air. When water/ethanol mixtures were used, the interactions were concluded to be due to ethanol condensation.

Confocal Raman microscopy experiments with water and water/ethanol mixtures on superhydrophobic surfaces gave evidence for water depletion and ethanol/air accumulation close to the surface. Force measurements using superhydrophobic surfaces showed extremely long-range interaction distances.

This work has provided evidence for air cavitation between hydrophobic surfaces in aqueous solution. It was also shown that the range and magnitude of interaction forces could, to some extent, be predicted by looking at certain surface features like structure,roughness and the overall length scales.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. xii, 73 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2012:52
hydrophobic surface, superhydrophobic surface, atomic force microscopy, surface forces, capillary forces, cavitaion, surface roughness, friction, wetting, confocal Raman, contact angles, surface preparation, Langmuir-Blodgett
National Category
Chemical Sciences
urn:nbn:se:kth:diva-103409 (URN)978-91-7501-506-4 (ISBN)
Public defence
2012-11-02, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)

QC 20121011

Available from: 2012-10-11 Created: 2012-10-11 Last updated: 2012-10-11Bibliographically approved

Open Access in DiVA

No full text

Other links

Publisher's full textScopus

Search in DiVA

By author/editor
Hansson, Petra M.Hormozan, YasharLinnros, JanClaesson, Per MartinSwerin, AgneThormann, Esben
By organisation
Surface and Corrosion ScienceMaterial Physics
In the same journal
Journal of Colloid and Interface Science
Other Chemistry Topics

Search outside of DiVA

GoogleGoogle Scholar
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Altmetric score

Total: 59 hits
ReferencesLink to record
Permanent link

Direct link