Using nanocomposite coatings to heal surface defects

Using computer simulations, we investigate the benefits of coating substrates that contain nanoscale defects with nanoparticle-filled polymer films. In particular, we focus on surfaces that contain a nanoscopic notch and use molecular dynamics (MD) simulations to determine the particle and polymer distribution on the damaged surface. The calculations reveal that a high volume fraction of relatively large particles are localized in the notch. Here, the polymer melt induces a depletion attraction between the particles and surface and thereby drives the nanoparticles into the defect. The time required for these relatively large particles to migrate to the notch is comparable to the time needed for the chains to move by approximately four radius of gyrations. The morphology obtained from the MD simulation serves as the input to the lattice spring model (LSM), which allows us to determine the mechanical properties of the nanocomposite-coated surface. The results show that the stress concentration at the notch tip is significantly reduced due to the presence of the nanoparticles. The application of such nanocomposite coatings could potentially yield defect-free surfaces that exhibit enhanced mechanical properties.