Ordering and Interactions of Gold Nanoparticles (AuNPs) with Fractional Surface Coverage of Ligands*

We studied the properties of self-assembled AuNPs monolayers. These monolayers are formed from solutions with varying thiol concentrations. We show that equilibrium between adsorbed thiols on Au cores and thiols in the bulk solution imply fractional coverage of the Au cores. The equilibrium coverage of AuNPs is adequately described by Langmuir adsorption kinetics, and, therefore, we interpret the way in which varying thiol concentration affects the nanoparticle-nanoparticle interactions as a function of surface coverage of the Au core [1]. We also examine the structure and general shape of the ligand envelope as a function of the surface coverage using molecular dynamics simulation and demonstrate that the equilibrium structure of the envelope and the deformation of that envelope generated by interaction between the AuNPs are coverage-dependent, so that the shape, depth, and position of the minimum of the potential of mean force display a systematic dependence on the ligand coverage [2].

[1] Reik et al, Soft Matter, 2019, DOI: 10.1039/c9sm01579e
[2] Liepold, et al, J. Chem. Phys., 2019, doi.org/10.1063/1.5064545