Aggregation of thiol coated gold nanoparticles: A simulation study on the effect of polymer coverage density and solvent

Molecular dynamics simulations have been carried out to investigate the effect of alkane thiol coverage density, terminal group and water solvent on the aggregation of thiol coated gold nanoparticles. The increase in polymer coverage density enhances the size of the aggregate as the van der Waals force of attraction dominates with the increase in the number of thiol chains. The change in the terminal group from methyl (hydrophobic) to hydroxy (hydrophilic) group modifies the size of the aggregate as the extent of interdigitation between thiol chains is reduced due to the hydrogen bond interactions between the hydroxy terminal groups. The water solvent does not much alter the aggregation of methyl terminated gold nanoparticles. It weakens the aggregation of hydroxy terminated gold nanoparticles due to the hydrophilic interaction between the water molecules and the hydroxy terminal groups.