Adsorption Dynamics of Surface-Modified Silica Nanoparticles at Solid-Liquid Interfaces

Understanding the adsorption dynamics of nanoparticles at solid-liquid interfaces is of paramount importance to engineer nanoparticles for a variety of applications. The nanoparticle surface chemistry is significant for controlling the adsorption dynamics. This study aimed to experimentally examine the adsorption of surface-modified round-shaped silica nanoparticles (with an average diameter of 12 nm), grafted with hydrophobic (propyl chains) and/or hydrophilic (polyethylene glycol chains) agents, at an aqueous solution-silica interface with spherical soda-lime glass beads (diameter of 3 mm) being used as adsorbents. While no measurable adsorption was observed for solely hydrophobic or hydrophilic nanoparticles, a considerable level of adsorption was detected for nanoparticles comprising both hydrophobic and hydrophilic agents. Various kinetic models were employed to model the adsorption dynamics of the responsive nanoparticles. The results demonstrated that the mixed diffusion kinetics models could predict the dynamics better than the adsorption diffusion models, indicating that the dynamics is controlled by a combination of liquid film diffusion, intra-particle diffusion, and mass action. Additionally, the adsorption of the surface-modified silica nanoparticles onto a mineral silica surface was examined using molecular dynamics simulations. The interaction energy for nanoparticles comprising both hydrophobic and hydrophilic agents was evaluated to be more favorable than that of solely hydrophobic or hydrophilic nanoparticles.

Automated summary

Understanding the adsorption dynamics of surface-modified silica nanoparticles at solid-liquid interfaces is crucial for their engineering in various applications. This study experimentally examined the adsorption behavior of round-shaped silica nanoparticles with hydrophobic and/or hydrophilic agents, and found that nanoparticles with both types of agents showed higher adsorption. Kinetic models were used to simulate the adsorption dynamics, and it was found that mixed diffusion kinetics models predicted the dynamics better.