Forces between Hydrophobic Solids in Concentrated Aqueous Salt Solution

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Date
2012-03-05
Journal Title
Journal ISSN
Volume Title
Publisher
American Physical Society
Abstract

Much research has focused on the discovery and description of long-ranged forces between hydrophobic solids immersed in water. Here we show that the force between high contact-angle solids in concentrated salt solution (1 M KCl) agrees very well with van der Waals forces calculated from Lifshitz theory for separations greater than 5 nm. The hydrophobic solids are octadecyltrichlorosilane-coated glass, with an advancing contact angle of 108 degrees. Thus, in 1 M salt solution, it is unnecessary to invoke the presence of a hydrophobic force at separations greater than 5 nm. Through measurement in salt solution, we avoid the necessity of accounting for large electrostatic forces that frequently occur in pure water and may obscure resolution of other forces.

Description
Keywords
Surfactant-coated surfaces, Monte carlo simulation, Long-range, Boundary-condition, Thin films, Attraction, Water, Microscopy, Particles, Interfaces, Physics
Citation
Mastropietro, Dean J. ; Ducker, William A., Mar 5, 2012. “Forces between Hydrophobic Solids in Concentrated Aqueous Salt Solution,” PHYSICAL REVIEW LETTERS 108(10): 106101. DOI: 10.1103/PhysRevLett.108.106101