Gold nanoparticle/polymer interfaces: All atom structures from molecular dynamics simulations

Molecular dynamics simulations have been performed to obtain detailed all-atom models of the interface between polystyrene (PS) and gold nanoparticles. Considering their relevance in the memory technology, systems containing gold nanoparticle included in PS polymer melts also in the presence of 8-hydroxyquinoline (8-HQ) molecules have been studied. Four different systems, including a coated or a noncoated nanoparticle, have been compared. Calculated radial density profiles show that the presence of noncoated nanoparticles in a polymer melt causes an ordering of polymer chains. A similar ordering behavior is found for the 8-HQ molecule. In the presence of a coated gold nanoparticle, calculated radial density profiles show much less order. When 8-HQ is present, this molecule is closer to the nanoparticle surface and when in contact with a coated nanoparticle it shows a partial penetration into the thiols layer. The molecular description obtained from simulations supports some of the hypothesis made on the basis of the experimental behavior of nonvolatile memory devices.