Influence of wetting properties on the long-range `hydrophobic' interaction between self-assembled alkylthiolate monolayers
2000 (English)In: Langmuir, ISSN 0743-7463, Vol. 16, no 5, 2177-2184 p.Article in journal (Refereed) Published
The effect of solid-liquid interfacial energy on the long-range attraction between self-assembled thiolate monolayers in water has been studied by direct force measurements. The solid-liquid interfacial energy was tuned by changing the properties of the solid surface: the thiolate monolayers were prepared by self-assembly of mixtures of methyl- and hydroxyl-functionalized alkylthiols onto thin gold films. The wetting properties were examined by contact angle measurements with the Wilhelmy plate method. Our results show that the shape of the long-ranged attractive force is sensitive to the advancing solid-liquid contact angle: whenever it exceeds 90° the force profiles are discontinuous and contains steps, whereas no attraction beyond the van der Waals force is observed for contact angles lower than 90°. We attribute the steps in the long-range attraction between hydrophobic surfaces to bridging of microscopic bubbles residing on the surfaces, and we conclude that the stability of these bubbles are related to macroscopic contact angles.
Place, publisher, year, edition, pages
2000. Vol. 16, no 5, 2177-2184 p.
Engineering and Technology
IdentifiersURN: urn:nbn:se:liu:diva-47681DOI: 10.1021/la9909650OAI: oai:DiVA.org:liu-47681DiVA: diva2:268577