On the mechanical interactions between TiO2 nanoparticles

In this work the mechanical interaction mechanisms between TiO2 nanoparticles at ambient conditions are investigated by using molecular dynamics (MD) and discrete element method (DEM) simulations in comparison to experimental findings. It is shown that the particle interaction forces are crucially determined by the nature of the surface adsorbed water layer of the particles. This dependence controls the characteristic trends of the interparticle forces at the nanoscale with humidity, surface roughness and hydrophilicity. From these insights, comprehensive equations are derived for the calculation of interparticle forces under ambient conditions at the nanoscale. The implementation of these equations into particle contact models enables the fast and accurate simulation of the mechanical behaviour of large nanoparticle assemblies and thus represents a link between the chemical properties of the particle surfaces and the macroscopic mechanical properties of entire nanoparticle films.