Nanoparticle Preparation

Preparation of Size Selected Au Nanoparticles Using Inverse Micelle Encapsulation

This research was conducted under the mentorship of Dr. Beatriz Roldan Cuenya.

General Nanoparticle Applications

  • Devices
    • Magnetic devices and storage
    • Sensors
  • Catalysis
    • Clean Ground Soil
    • Air Purification
    • Outgas Purification
    • Hydrogen Production (fuel cells)
    • Selective Partial Oxidation

Au Nanoparticles in Specific

  • Au nanoshells with infrared laser to kill cancerous cells [L.R. Hrisch, et al. PNAS 100 (2003) 13459]
  • Arthritis Drugs [R.C. Edler, et al. JACS 107 (1985) 5024]
  • Biohazard Detection
  • Manufacturing of emulsion-bas paints, wall -paper paste and wood glue
  • Production of cheaper solar cells

Catalysis!! CO Oxidation and NOx Reduction

Catalysis

  • Science of enhancing chemical reaction rates and selectivities based on the use of materials (catalysts) that are not consumed during the course of the reaction. [R. Somorjai, Catal. Today (2005)]

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Organic Encapsulation

Reasons for Use

  1. Size/Shape Selection
  2. Large Surface Areas
  3. Self-Assembly
  4. Low CostMicelle Formation

Micelle Formation

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On the right there isa micelle andd on the left there is an inverse micelle. A micelled is greated when placed in water (polar) and an inverse micelled is formed when placed in an oil (toluene in the case of this research).

How It's Done

  1. Dissolve Diblock Copolymer [Polystyrene-2-vinylpyridine (PS-2-PVP)] in toluene, which results in inverse micelle formation.
  2. Load micelles with metal precursor HAuCl4.

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  3. Gold complex attaches to the pyridine group.
  4. Dip-coat SiO2/Si(111) at 100 µm/s substrate into solution to obtain 1 ML of polymer-encapsulated nanoparticles.
  5. Polymer removal, Au reduction, using Hydrogen or Oxygen plasma tratment 10 min. (5mTorr, DC 60V, 300W coil)

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Langmuir 16 (2000) 417. Roldán et al. JACS 125 (2003) 12926.

Size and Distance

Size of Au particle is controlled by:

  • Amount of HAuCl added
  • Length of block copolymer head

Distance between clusters controlled by:

  • Length of block copolymer tail

Atomic Force Microscopy (AFM)

Error: Could ot load image. The AFM was used for the characterization of the particles. It was my faithful companion throughout hours of toil.
Through this analysis technique a before and after "picture" can be taken of the surface before and after the polymer removal.
P1333_S2VP

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P3671_22VP

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Conclusions

  • Polymer P1333_S2VP produced micelles and nanoparticles of high uniformity in size and highly dispersed on the substrate.
  • Ongoing modifications in the sample preparation procedure should increase uniformity and prevent agglomeration.
    • Change the hydrophilicity of the SiO2 substrate.
    • Change the substrate completley; we plan on using TiO2.

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