Adsorption of colloid nanoparticles on carbon nanotubes studied by means of molecular dynamics simulations

In this work we deal with interactions of colloid nanoparticles with carbon nanotubes across water and some organic solvents. The aim of this work is to track the range of dispersion interactions between these two species as functions of their structure, local geometry, role of solvents applied, etc. The studies are based on molecular dynamics simulations and the structure of carbon nanotubes (single and multi-walled) are described according to Adaptive Intermolecular Reactive Empirical Bond Order potential while interaction of colloid nanoparticles with other components of the system involves the Hamaker potential. Thus, we are able to study energetic effects related to position of nanoparticles on nanotubes surfaces, nanotubes flexibility and effects related to chemical nature of solvents used. We found that single walled nanotubes interact stronger at sidewalls while multi-walled on tips. Metallic nanoparticles lead to deformation of the nanotubes structures and reveal huge energy of dispersion interactions, comparable to chemical bonds energy. Silica covered metallic nanoparticles interact weakly and their behavior on the nanotubes surfaces can be additionally affected by their charges when water is considered as solvent. We found that in that case the diffusion of silica covered nanoparticles is anomalous and obeys the sub-diffusion mechanism in crowded systems. We also found that preferential location of nanoparticles on nanotubes tips is difficult to realize by controlling only physical conditions under which the system is considered.

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► We study interactions between carbon nanotubes and colloid nanoparticles.
► We found large energetic barrier between tip and side positions on nanotube surface.
► Multi-walled carbon nanotubes exhibit larger adsorption energy on tip positions.
► Carbon nanotubes behave like rigid bodies in interaction with silica nanoparticles.