Ligand-Exchange Dynamics on Gold Nanocrystals: Direct Monitoring of Nanoscale Polyvinylpyrrolidone-Thiol Domain Surface Morphology.
We report direct high-resolution monitoring of an evolving mixed nanodomain surface morphology during thiol adsorption on polyvinylpyrrolidone (PVP)-stabilized single crystal gold nanocrystals. The thiol adsorption and replacement dynamics are much more complex than a simple complete substitution of the initial polymer ligand. We observed that during ligand exchange with linear thiol, the nanocrystal surface evolved from an initial 1 nm uniform PVP coating into a remarkably stable network of globular PVP domains 20-100 nm in size and ∼4 nm in height surrounded by thiol self-assembled monolayers. The final stability of such a mixed thiol-PVP surface morphology can possibly be attributed to the interfacial energy reduction from partially solvophilic surfaces and the entropic gain from mixed ligand surface layers. The ligand-exchange dynamics and the unusual equilibrium morphology revealed here provide important insights into both displacement dynamics of surface-bound molecules and the nanoscale peculiarities of surface functionalization of colloidal metal substrates.
School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
Shuaidi
0000-0001-9949-8301
S
Zhang
School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
Sunghan
S
Kim
School of Materials Science and Engineering, Georgia Institute of Technology , Atlanta, Georgia 30332-0245, United States.
Vladimir V
0000-0001-5489-0967
VV
Tsukruk