Hard core-soft shell particles near repulsive interfaces: interplay between adsorption, aggregation and diffusion

TL;DR

This study uses Langevin Dynamics simulations to explore how polymer-grafted nanoparticles with core-softened interactions behave near repulsive surfaces, revealing temperature-dependent adsorption and diffusion phenomena related to their interaction scales.

Contribution

It introduces a detailed simulation analysis of nanoparticle adsorption and dynamics near repulsive interfaces considering a core-softened potential, highlighting temperature effects on these processes.

Findings

Adsorption maxima linked to fluid-cluster transition at low temperatures.

Long-range repulsion influences particle arrangement and diffusion.

Temperature increase reduces adsorption maxima by enabling particles to overcome repulsive barriers.

Abstract

The behavior of colloidal particles with a hard core and a soft shell has attracted the attention for researchers in the physical-chemistry interface not only due the large number of applications, but due the unique properties of these systems in bulk and at interfaces. The adsorption at the boundary of two phases can provide information about the molecular arrangement. In this way, we perform Langevin Dynamics simulations of polymer-grafted nanoparticles. We employed a recently obtained core-softened potential to analyze the relation between adsorption, structure and dynamic properties of the nanoparticles near a solid repulsive surface. Two cases were considered: flat or structured walls. At low temperatures, a maxima is observed in the adsorption. It is related to a fluid to clusters transition and with a minima in the contact layer diffusion - and is explained by the competition between the scales in the core-softened interaction. Due the long range repulsion, the particles stay at the distance correspondent to this length scale at low densities, and overcome the repulsive barrier as the packing increases, However, increasing the temperature, the gain in kinetic energy allows the colloids to overcome the long range repulsion barrier even at low densities. As consequence, there is no competition and no maxima was observed in the adsorption.