1 research outputs found
Contact Forces between TiO<sub>2</sub> Nanoparticles Governed by an Interplay of Adsorbed Water Layers and Roughness
Interparticle forces govern the mechanical
behavior of granular
matter and direct the hierarchical assembling of nanoparticles into
supramolecular structures. Understanding how these forces change under
different ambient conditions would directly benefit industrial-scale
nanoparticle processing units such as filtering and fluidization.
Here we rationalize and quantify the contributions of dispersion,
capillary, and solvation forces between hydrophilic TiO<sub>2</sub> nanoparticles with sub-10 nm diameter and show that the humidity
dependence of the interparticle forces is governed by a delicate interplay
between the structure of adsorbed water layers and the surface roughness.
All-atom molecular dynamics modeling supported by force-spectroscopy
experiments reveals an unexpected decrease in the contact forces at
increasing humidity for nearly spherical particles, while the forces
between rough particles are insensitive to strong humidity changes.
Our results also frame the limits of applicability of discrete solvation
and continuum capillary theories in a regime where interparticle forces
are dominated by the molecular nature of surface adsorbates