Nanoscience

Solvent-ligand Interactions Govern Stabilizing Repulsions between Colloidal Metal Oxide Nanocrystals

Authors

Abstract

Nanocrystal interactions in solvent influence colloidal stability and dictate self-assembly outcomes. Small-angle X-ray scattering is used to study how dilute oleate-capped In2O3 nanocrystals with 7–19 nm core diameters interact when dispersed in a series of nonpolar solvents. Osmotic second virial coefficient analysis finds toluene-dispersed NCs interact like hard spheres with diameters comprising the inorganic core and a ligand-solvent corona with a core-size independent thickness. Dynamic light scattering measurements show consistent hydrodynamic and thermodynamic size scaling, further indicating hard-sphere-like behavior. By choosing solvents with stronger ligand-solvent attractions, the effective ligand-solvent corona thickness can be increased by approximately one solvent molecular diameter (0.8 nm). These results highlight the role that solvent choice could play in designing nanocrystal contact spacing, important in the initial stages of superlattice assembly or for modulating the optical response of plasmonic or photoluminescent colloidal gel networks.

Content

Thumbnail image of CKO_Manuscript.pdf

Supplementary material

Thumbnail image of CKO_Supporting Information.pdf
Solvent-ligand Interactions Govern Stabilizing Repulsions between Colloidal Metal Oxide Nanocrystals
Nanocrystal interactions in solvent influence colloidal stability and dictate self-assembly outcomes. Small-angle X-ray scattering is used to study how dilute oleate-capped In2O3 nanocrystals with 7–19 nm core diameters interact when dispersed in a series of nonpolar solvents. Osmotic second virial coefficient analysis finds toluene-dispersed NCs interact like hard spheres with diameters comprising the inorganic core and a ligand-solvent corona with a core-size independent thickness. Dynamic light scattering measurements show consistent hydrodynamic and thermodynamic size scaling, further indicating hard-sphere-like behavior. By choosing solvents with stronger ligand-solvent attractions, the effective ligand-solvent corona thickness can be increased by approximately one solvent molecular diameter (0.8 nm). These results highlight the role that solvent choice could play in designing nanocrystal contact spacing, important in the initial stages of superlattice assembly or for modulating the optical response of plasmonic or photoluminescent colloidal gel networks.