Publications

Mechanics of Gold Nanoparticle Superlattices at High Hydrostatic Pressure

Srivastava, Ishan S.; Peters, Brandon L.; Lane, James M.; Fan, Hongyou F.; Grest, Gary S.; Salerno, Michael S.

Pressure-driven assembly of ligand-grafted gold nanoparticle superlattices is a promising approach for fabricating gold nanostructures, such as nanowires and nanosheets. However, optimizing this fabrication method requires an understanding of the mechanics of their complex hierarchical assemblies at high pressures. We use molecular dynamics simulations to characterize the response of alkanethiol-grafted gold nanoparticle superlattices to applied hydrostatic pressures up to 15 GPa, and demonstrate that the internal mechanics significantly depend on ligand length. At low pressures, intrinsic voids govern the mechanics of pressure-induced compaction, and the dynamics of collapse of these voids under pressure depend significantly on ligand length. These microstructural observations correlate well with the observed trends in bulk modulus and elastic constants. For the shortest ligands at high pressures, coating failure leads to gold core-core contact, an augur of irreversible response and eventual sintering. This behavior was unexpected under hydrostatic loading, and was only observed for the shortest ligands.