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

Authors: GOMEZ-FLORES, ALLAN - Chonbuk National University; Bradford, Scott; WU, LEI - Ohio University; KIM, HYUNJUNG - Chonbuk National University

Submitted to: Colloids and Surfaces A: Physicochemical and Engineering Aspects
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/8/2019
Publication Date: 8/9/2019
Citation: Gomez-Flores, A., Bradford, S.A., Wu, L., Kim, H. 2019. Interaction energies for hollow and solid cylinders: Role of aspect ratio and particle orientation. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 580. https://doi.org/10.1016/j.colsurfa.2019.123781.
DOI: https://doi.org/10.1016/j.colsurfa.2019.123781

Interpretive Summary: Cylindrical shaped particles such as bacteria and carbon nanotubes are used in many industrial and environmental applications. However, traditional approaches to determine the particle interactions with surfaces assume a spherical geometry. In this work, we quantify the interaction of cylindrical particles with surfaces and demonstrate the sensitivity of results to the particle length and width, orientation with the surface, and interior properties. In general, greater interactions are predicted for solid than hollow cylinders, and for cylindrical particles having small widths with their lengths oriented perpendicular to the surface. This information will be of interests to scientists and engineers that use cylindrical particles for specific purposes.

Technical 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 (p/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.