1 research outputs found
Interdependent Roles of Electrostatics and Surface Functionalization on the Adhesion Strengths of Nanodiamonds to Gold in Aqueous Environments Revealed by Molecular Dynamics Simulations
Molecular dynamics
simulations demonstrate that adhesion strengths
as a function of charge for aqueous nanodiamonds (NDs) interacting
with a gold substrate result from an interdependence of electrostatics
and surface functionalization. The simulations reveal a water layer
containing Na<sup>+</sup> counterions between a negative ND with surface
−COO<sup>–</sup> functional groups that is not present
for a positively charged ND with −NH<sub>3</sub><sup>+</sup> functional groups. The closer proximity of the positive ND to the
gold surface and the lack of cancelation of electrostatic interactions
due to counterions and the water layer lead to an electrostatic adhesion
force for the positive ND that is nearly three times larger than that
of the negative ND. Prior interpretations of experimental tribological
studies of ND–gold systems suggested that electrostatics or
surface functionalization could be responsible for observed adhesion
strength differences. The present work demonstrates how these two
effects work together in determining adhesion for this system