Multidimensional Characterization of Mixed Ligand Nanoparticles Using Small Angle Neutron Scattering

The properties of ligand protected gold nanoparticles are determined by the synergistic interplay of their structural components, including the metal core, the ligand shell, and the solvation layer. However, the simultaneous characterization of all these components remains a major challenge given their disparate chemical nature. In the case of mixed ligand nanoparticles, this task becomes daunting due to the presence of intercorrelated additional parameters such as the ligand ratio, ligand spatial distribution, and solvation of the heterogeneous ligand shell. Here we show that small angle neutron scattering (SANS) is a tool capable of simultaneously characterizing the core and the ligand shell of monodisperse mixed ligand gold nanoparticles. We systematically examine how each parameter (e.g., the core size, the thickness, composition and the spatial heterogeneity of the ligand shell) affects nanoparticles' scattering profile. Quantitative information on these parameters is retrieved using analytical fitting as well as 3D modeling. Importantly, we show that SANS can evaluate the solvation degree of mixed ligand protected gold nanoparticles, a challenging task for any other characterization methods.