Healing Surface Defects with Nanoparticle-Filled Polymer Coatings: Effect of Particle Geometry

Abstract

Using computational models, we investigate how the aspect ratio of nanoparticle fillers within a polymer coating affects the ability of the film to heal nanoscale defects in the underlying substrate. We first consider the interactions between the filled polymer melt and a flat surface and show that the depletion attraction between the nanoparticles and this substrate depends strongly on this aspect ratio. In particular, the rodlike particles experience a significantly stronger attraction to the substrate than spherical fillers. We quantify these interactions by measuring the effective potential between a particle and surface as well as between two particles in the melt. We then consider the case of a surface that contains a nanoscopic notch, which represents the damaged region. We show how tailoring the particles' aspect ratio provides a means of optimizing the localization of the particles into the notch. Morphologies obtained from molecular dynamics simulations are then used as input to a lattice spring...