Pressure and Composition Effects on a Common Nanoparticle Ligand–Solvent Pair

Abstract

The effect of pressure on the properties of nanoparticles is a growing area of investigation. These measurements are typically performed in a colloidal suspension; however, pressure-induced changes in the interactions between the nanoparticle surface and the solvent are often neglected. Here, we report vibrational spectroscopy of a common nanoparticle ligand, 1-dodecanethiol, and a common solvent, toluene, under pressure. We find that the pressure-induced phase change of the 1dodecanethiol is altered by the presence of toluene and that change depends on the concentration of the free ligand in the solution. At near-equal concentrations, phase segregation is observed and the dodecanethiol crystallizes independently from the toluene. On the other hand, at unequal concentrations, concerted phase transitions are observed in the dodecanethiol and toluene, and a disordered conformation of dodecanethiol is maintained under much higher pressures. These results shed light on the pressure-induced changes in intermolecular interactions between nanoparticle ligands and solvents, which must be considered in the design of high-pressure investigations of colloidal nanoparticles.

The influence of PEGylated gold nanoparticles on the solidification of alcohols

“…S1 in the ESI†), thus proving that the PEG-SH concentration scales with the molar gold concentration in the colloid. Notably, it has recently been shown elsewhere 24 that the pressure-induced phase transition of the 1-dodecanethiol, a common AuNP ligand, is modified by interactions with solvent molecules, i.e. , toluene, emphasizing the importance of ligand–solvent interactions in the structural evolution of these colloids with pressure.…”