Study of the Adsorption Behaviors of Amphiphilic Gold Nanoparticles at the Liquid–Liquid Interface Dependent on Surface Properties

This study investigates the effect of the ratio of hydrophobic to hydrophilic ligands on the surface of gold nanoparticles (AuNPs) on the adsorption of AuNPs at the hexane–water interface. Depending on the ratio, experimental results showed different adsorption behaviors of amphiphilic AuNPs at the interface. Thus, several isotherm models were employed to characterize the adsorption behaviors. The Langmuir model describes homogeneous monolayer adsorption of AuNPs with ratios of 0.41 and lower. The Freundlich model describes heterogeneous multilayer adsorption of AuNPs with ratios of 0.41 and higher. The Redlich–Peterson model is capable of fitting the experimental data for all ratios. Using the models, the maximum uptake, the equilibrium constant, and the interparticle distance for the adsorbed AuNPs at the interface were evaluated. To the best of our knowledge, systemic studies of nanoparticle (NP) adsorption at the interface depending on NP surface properties have not been previously reported.