Evidence for phase separation of ethanol-water mixtures at the hydrogen terminated nanocrystalline diamond surface

• Published in: The Journal of chemical physics Vol. 137; no. 4; p. 044702
• Main Authors: Janssens, Stoffel D, Drijkoningen, Sien, Saitner, Marc, Boyen, Hans-Gerd, Wagner, Patrick, Larsson, Karin, Haenen, Ken
• Format: Journal Article
• Language: English
• Published: United States 28-07-2012
• Subjects: Diamond - chemistry; Ethanol - chemistry; Hydrogen - chemistry; Hydrophobic and Hydrophilic Interactions; Nanoparticles - chemistry; Surface Properties; Water - chemistry
• ISSN: 1089-7690
• DOI: 10.1063/1.4738192

Interactions between ethanol-water mixtures and a hydrophobic hydrogen terminated nanocrystalline diamond surface, are investigated by sessile drop contact angle measurements. The surface free energy of the hydrophobic surface, obtained with pure liquids, differs strongly from values obtained by ethanol-water mixtures. Here, a model which explains this difference is presented. The model suggests that, due to a higher affinity of ethanol for the hydrophobic surface, when compared to water, a phase separation occurs when a mixture of both liquids is in contact with the H-terminated diamond surface. These results are supported by a computational study giving insight in the affinity and related interaction at the liquid-solid interface.