Microwave-assisted synthesis of oleic acid-capped silver nanoparticles as lubricant additives

Abstract

Recently, metal nanoparticles have been studied extensively as lubricant additives. Owning to their nanometer size, the nanoparticles can fill micro defects on contacting surfaces, acting as repairing agents. In this work, we describe a simple and fast method to fabricate monodisperse silver nanoparticles using oleic acid as a capping agent. In particular, silver nitrate was reduced by oleylamine in the oleic acid medium using acetonitrile as a co-solvent, and the reaction was heated by a microwave source. Results showed that the particle size was greatly affected by varying the reductant concentration. The average diameter of synthesized nanoparticles ranges from 3.0 nm to 4.0 nm at optimum conditions. The dispersibility in the oil of the product is attributed to the long-chain alkyl from fatty acid grafted on the surface layer, which constitutes about 21% of the weight of the nanoparticles as determined by thermogravimetric analysis.