373374 Colloidal Stability of Ligand-Stabilized Gold Nanoparticles

Thursday, November 20, 2014: 1:30 PM
213 (Hilton Atlanta)
Ashutosh Rathi1, Vincent Rotello2, Richard Vachet2 and David Ford1, (1)Chemical Engineering, University of Massachusetts Amherst, Amherst, MA, (2)Chemistry, University of Massachusetts Amherst, Amherst, MA

Gold nanoparticles (NP), coated with organic ligands for stabilization and functionalization, are being increasingly used in nano- and bio-technology applications.  The ultimate fate of such NP in the environment is a matter of increasing concern.  As a first step, it would be useful to have a predictive model for the stability of the NP against self-aggregation in various aqueous media.  When NP are very small (less than 100 nm), traditional models like DLVO fail to predict the stability, leading to incorporation of so-called extra-DLVO forces that are less understood.  In this work we carry out a systematic study of the short-time aggregation of a certain class of ligand-stabilized gold NP using a combination of experiment and modeling.  The NP are prepared with various gold cores, ranging from 2-6 nm in size, and coated with alkanethiols that terminate in a short hydrophilic segment and a charged head group (which can be varied).  Dynamic light scattering measurements are used to calculate the stability ratio, which is directly related to the total interaction potential, for a given NP-solvent system.  Atomistic modeling gives an independent first-principles prediction that aids in understanding the experimental results.  Finally, classical models (in the extra-DLVO regime) are parameterized using the quantitative understanding gained from these techniques.

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See more of this Session: Colloidal Dispersions II
See more of this Group/Topical: Engineering Sciences and Fundamentals