Synthesis and Characterization of Metal Nanoparticles and the Formation of Metal-Polymer Nanocomposites
- PDF / 1,979,938 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 29 Downloads / 197 Views
I6.10.1
Synthesis and Characterization of Metal Nanoparticles and the Formation of MetalPolymer Nanocomposites Anshu A. Pradhan, 1,3 S. Ismat Shah1,2,3 and Lisa Pakstis1 1 Department of Materials Science and Engineering 2 Department of Physics and Astronomy University of Delaware, Newark, DE 19716, USA 3 Fraunhofer Center for Manufacturing and Advanced Materials, Newark, DE 19711, USA ABSTRACT Metal nanoparticles are highly prone to oxidation due to their high surface energy and affinity for oxygen which can lead to the complete oxidation of the particles. Studying and utilizing the unique properties of metal nanoparticles requires minimizing their interaction with the atmosphere. We have used the co-condensation technique to synthesize suspensions of metal nanoparticles in isopropanol. The solvent protects the nanoparticles from the atmosphere and minimizes agglomeration of the nanoparticles. The particles showed a lognormal distribution and the average particle size was below 20nm. Polymer-metal nanocomposites were made by dispersing the metal nanoparticles in PMMA matrix by spin coating and solution casting. Adherent films, fibers and free standing films could be obtained by varying the process conditions. The SEM images show that the nanoparticles in the spun coated films were nonagglomerated and well dispersed over a wide area. Morphology of the spun coated films was different from the solution cast films. Electrically conducting films having interconnected silver particle network could be obtained. Cytotoxicity studies show that the silver nanoparticles and the PMMA-Ag nanocomposite films are antibacterial in nature. We have also dispersed the nanoparticle into pump oil and measured the thermal conductivity of the resultant mixture. The thermal conductivity of the oil could be increased by over 50% by adding an extremely small fraction of the silver nanoparticles. INTRODUCTION Metal nanoparticles have received tremendous interest due to their unique optical, electrical and magnetic properties.[1-4] Several chemical and vacuum techniques have been used to synthesize metal nanoparticles.[5,6] In general, chemical techniques produce smaller nanoparticles with a narrower particle size distribution, while vacuum techniques produce higher purity nanoparticles. In this paper, we report on the synthesis of silver nanoparticles by CoCondensation (COCON) technique which combines the advantages of chemical and vacuum routes of nanoparticle synthesis. COCON is derived from an earlier technique called Vacuum Evaporation onto a Running Oil Substrate (VEROS) demonstrated by Yatsuya and his coworkers[7]. The technique was modified by Klablunde[6,8] who used an organic liquid in place of the oil used in VEROS. The COCON technique involves the co-deposition of metal vapors from an evaporation source, and a suitable solvent onto the cryogenically cooled walls of an evacuated chamber. The supercooling of the metal vapors as they move away from the evaporation source leads to the formation of metallic nuclei. These nuclei are dep
Data Loading...
