Interaction energies for hollow and solid cylinders: Role of aspect ratio and particle orientation

Abstract

Particles of various shapes (e.g., spheres or rods), sizes (e.g., nm to microns), interiors (e.g., solid or hollow), and materials are used in many industrial and environmental applications. The Derjaguin-Landau-Verwey-Overbeek (DLVO) theory has commonly been used to calculate and predict the adhesive interaction of these particles with solid surfaces. However, DLVO theory treats these particles as equivalent spheres for simplicity ignoring shape in numerous cases. The surface element integration (SEI) approach allows DLVO theory to be extended for different particle shapes, orientations, and interiors. In this study, the SEI approach was applied to calculate the interaction energy between hollow and solid cylinders with a flat surface. The effect of aspect ratio and particle orientation on interaction energies was investigated under different solution chemistry conditions. Our study is relevant for an extensive range of particle aspect ratios, ranging from nanosized particles such as carbon nanotubes or nanowires, which have high aspect ratios, to micron-sized particles such as bacteria, which have low aspect ratios. The energy barrier tended to increase when the angle that the larger axis of the particle made with the normal to the surface changed from perpendicular (0 rad) to parallel (pi/2 rad). The aspect ratio did not affect the trend of the energy barrier for solid (200-1000) and hollow (25-1000) cylinders of relatively high aspect ratios, but it produces a non-monotonic trend for solid (2-100) and hollow (2-10) cylinders of low aspect ratios. The present study advances our understanding of adhesive interactions for particles having a wide range of aspect ratios and interior properties at various orientations with the surface.