Water Greatly Impacts on the Nanomechanical Degradation of Functionalized Surfaces

Abstract

The functionalization of gold nanoparticles by attaching polyethylene glycol (PEG) chains via sulfur-based anchors is a major approach in technological and nanomedicinal applications. Still, the molecular mechanisms of nanomechanical degradation of such PEGylated gold interfaces exposed to aqueous environments remain unknown. Using isotensional ab initio simulations we find that water plays a pivotal role in both, purely mechanical rupture and mechanochemical degradation scenarios. These are not determined by force transduction, but rather by distinct interactions of water molecules with the chemical anchors that attach PEG to gold. Based on these insights, shielding against solvation by water is expected to significantly increase their stability toward mechanically-assisted degradation.