Solvation Forces Near Hydrophobic Surfaces: A Classical Density Functional Theory Study.

Area of Science:

• Physical Chemistry
• Colloid and Surface Science
• Computational Physics

Background:

• Understanding solvation interactions between hydrophobic surfaces is crucial in various scientific fields.
• These interactions are influenced by molecular properties of the solvent and surface characteristics.

Purpose of the Study:

• To model and characterize solvation interactions between hydrophobic surfaces using classical density functional theory (DFT).
• To investigate the nature of these interactions, including depletion attraction and bipower law forces, at different surface separations.

Main Methods:

• Classical density functional theory (DFT) was employed to model solvation interactions.
• Simulations considered model hydrophobic surfaces like bubbles and nonpolar solids.
• Calculated molecular distribution and hydrophobic excess force in the interlaying solvent.

Main Results:

• Hydrophobic interactions are characterized by depletion attraction at small separations and a bipower law at large separations.
• The study identified contributions from van der Waals (vdW) and Coulombic interactions, as well as molecular thermal motion and finite volume.
• Analytical and numerical DFT solutions showed good agreement, predicting attractive forces with potential for repulsion under specific conditions.

Conclusions:

• The theoretical model accurately predicts adhesion energies, aligning with experimental findings.
• DFT provides a robust framework for understanding complex solvation phenomena at interfaces.
• The findings offer insights into the fundamental forces governing hydrophobic interactions.