Molecular origins of fluorocarbon hydrophobicity
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- 19 July 2010
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 107 (31), 13603-13607
- https://doi.org/10.1073/pnas.0915169107
Abstract
We have undertaken atomistic molecular simulations to systematically determine the structural contributions to the hydrophobicity of fluorinated solutes and surfaces compared to the corresponding hydrocarbon, yielding a unified explanation for these phenomena. We have transformed a short chain alkane, n-octane, to n-perfluorooctane in stages. The free-energy changes and the entropic components calculated for each transformation stage yield considerable insight into the relevant physics. To evaluate the effect of a surface, we have also conducted contact-angle simulations of water on self-assembled monolayers of hydrocarbon and fluorocarbon thiols. Our results, which are consistent with experimental observations, indicate that the hydrophobicity of the fluorocarbon, whether the interaction with water is as solute or as surface, is due to its "fatness." In solution, the extra work of cavity formation to accommodate a fluorocarbon, compared to a hydrocarbon, is not offset by enhanced energetic interactions with water. The enhanced hydrophobicity of fluorinated surfaces arises because fluorocarbons pack less densely on surfaces leading to poorer van der Waals interactions with water. We find that interaction of water with a hydrophobic solute/surface is primarily a function of van der Waals interactions and is substantially independent of electrostatic interactions. This independence is primarily due to the strong tendency of water at room temperature to maintain its hydrogen bonding network structure at an interface lacking hydrophilic sites.Keywords
This publication has 44 references indexed in Scilit:
- Characterizing hydrophobicity of interfaces by using cavity formation, solute binding, and water correlationsProceedings of the National Academy of Sciences, 2009
- Coexistence and transition between Cassie and Wenzel state on pillared hydrophobic surfaceProceedings of the National Academy of Sciences, 2009
- What do we need for a superhydrophobic surface? A review on the recent progress in the preparation of superhydrophobic surfacesChemical Society Reviews, 2007
- GROMACS: Fast, flexible, and freeJournal of Computational Chemistry, 2005
- Interfaces and the driving force of hydrophobic assemblyNature, 2005
- Oriented Surface Dipoles Strongly Influence Interfacial WettabilitiesJournal of the American Chemical Society, 1999
- VMD: Visual molecular dynamicsJournal of Molecular Graphics, 1996
- Wetting of crystalline polymer surfaces: A molecular dynamics simulationThe Journal of Chemical Physics, 1995
- The equilibrium solvation structure for the solvent-separated hydrophobic bondThe Journal of Chemical Physics, 1985
- Molecular dynamics with coupling to an external bathThe Journal of Chemical Physics, 1984