Mechanical characterization of nanoporous Au modified with self-assembled monolayers

The surface of nanoporous Au was modified with self-assembled monolayers (SAMs) of 6-mercapto-1-hexanol and the hardness tests were performed on the SAM-modified and non-modified nanoporous Au to investigate the effects of SAM modification on the mechanical properties of nanoporous Au. In addition, the origin of the chemomechanical effects was investigated by first principles shear test simulations on an Au–S alloy. The SAM-modified nanoporous Au showed lower hardness than the non-modified nanoporous Au. The loading rate dependence tests showed that the activation volume was low for both, indicating that events of a short range play an important role in deformation of nanoporous Au, regardless of whether the nanoporous Au was modified with SAMs. It was suggested from the simulations that the lower hardness for the SAM-modified nanoporous Au is because movement of dislocation endpoints at the surface is facilitated by chemical effects of Au–S bonding.