title: Au nanoparticle clusters from deposition of a coalescing emulsion.
abstract: OBJECTIVE
  Nanoparticle adsorption at the oil-water interface in an unstable, coalescing emulsion leads to cluster formation.
  
  
  METHODS
  Stable suspensions of clusters are prepared using a facile, two-step procedure involving few reagents and neither thiolated compounds nor chlorinated solvents. First, colloidal gold nanoparticles are assembled at the aqueous-hexanol interface in an emulsion that rapidly coalesces and spontaneously deposits a film on the interior surface of the glass container. The film is dissolved in ethanol with sonication to disperse the clusters. The film and clusters are characterized by transmission electron and atomic force microscopies as well as ultraviolet-visible spectrometry.
  
  
  RESULTS
  Clusters are observed to contain as few as 8 to as many as 24 Au nanoparticles. The clusters are anisotropic and can also be formed from larger nanoparticles. Hydrophobic and hydrophilic interactions are implicated in the formation of these clusters within the interfacial tension gradients of a coalescing emulsion. The clusters can be re-suspended in ethanol and water, maximizing the utility of these clusters with an extinction band in the near-Infrared region of the electromagnetic spectrum.
authors: 1600 Campus Road, Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA.
authors: Benjamin D
authors: BD
authors: Clark
authors: 1600 Campus Road, Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA.
authors: Anton R
authors: AR
authors: Molina
authors: 1600 Campus Road, Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA.
authors: Gary G
authors: GG
authors: Martin
authors: 1600 Campus Road, Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA.
authors: Jenny W
authors: JW
authors: Wang
authors: 1600 Campus Road, Department of Chemistry, Occidental College, Los Angeles, CA 90041, USA. Electronic address: emspain@oxy.edu.
authors: Eileen M
authors: EM
authors: Spain
keywords: Anisotropic clusters of nanoparticles; Au nanoparticles; Cluster formation; Coalescing emulsion; Nanoparticle adsorption; Surface tension gradients