The interaction of charged nanoparticles at interfaces

TL;DR

This study investigates how charged nanoparticles interact at surfactant bilayer interfaces, confirming classical electrostatic and van der Waals models and refuting the occurrence of like-charge attraction in such systems.

Contribution

It demonstrates that charged nanoparticles at soft interfaces are accurately described by classical electrostatic and van der Waals interactions, challenging previous reports of like-charge attraction.

Findings

Interactions are well described by DLVO and dipolar models.

Charged nanoparticles do not exhibit like-charge attraction at interfaces.

Classical models suffice to explain nanoparticle behavior at soft interfaces.

Abstract

We study charged nanoparticles adsorbed onto surfactant bilayers using small-angle scattering of synchrotron radiation. The in-plane interaction of the particles is well described by a DLVO component (measured independently in solution) and a repulsive dipolar interaction due to the presence of the interface, with an amplitude close to the theoretical prediction. We prove that charged nanoparticles at soft interfaces are well described by the classical model of Poisson-Boltzmann and van der Waals terms; as a corollary, they do not experience the like-charge attraction reported in the literature for some systems of micron-sized spheres at interfaces.