Geometric effects on non-DLVO forces: relevance for nanosystems

Area of Science:

• Colloid and Surface Science
• Physical Chemistry
• Nanotechnology

Background:

• Non-DLVO forces like Lewis acid-base and solvation are crucial in systems such as bacterial adhesion and nanoparticle stability.
• Accurate modeling of these forces is essential for understanding interactions at the nanoscale, including atomic force microscopy (AFM) measurements.

Purpose of the Study:

• To derive analytical force/potential versus distance profiles for Lewis acid-base and solvation forces using the surface element integration (SEI) method.
• To compare SEI-derived expressions with the Derjaguin approximation, assessing the impact of surface curvature on interaction profiles.
• To provide corrections for acid-base force calculations and determine the suitability of approximations for solvation forces.

Main Methods:

• Application of the surface element integration (SEI) method to derive force/potential profiles.
• Comparison of SEI results with the Derjaguin approximation for sphere-flat plate and sphere-sphere geometries.
• Analysis of deviations based on particle size and decay length (λ) for Lewis acid-base and solvation forces.

Main Results:

• Significant deviations between SEI and Derjaguin approximations for Lewis acid-base interactions were observed for particles up to 40 nm in diameter (with λ = 1 nm).
• The study highlights the importance of accounting for curvature in acid-base interactions, even for simple geometries.
• For solvation forces, deviations were minimal due to their oscillatory nature and shorter decay length, suggesting the Derjaguin approximation is generally suitable.

Conclusions:

• The SEI method provides accurate force profiles, revealing significant curvature effects on acid-base interactions that necessitate corrections to Derjaguin-based calculations.
• The Derjaguin approximation remains suitable for modeling solvation forces due to their intrinsic properties.
• This research offers practical insights for refining nanoscale interaction models in diverse scientific applications.