Synthesis and Characterization of Silver Nanoparticles in Reverse Micelles of Nonionic Surfactants and in Their Mixed Micelles with AOT

Abstract

Stable silver nanoparticles have been obtained in reverse micelles of known and available nonionic surfactants, sorbitan monooleate (Span 80) and tetraethoxylated dodecanol and p-nonylphenol (Brij 30 and Tergitol NP-4, respectively), in n-decane. The obtained nanoparticles have been characterized using a number of physicochemical methods. The stability, hydrodynamic diameter, and electrokinetic potential of the nanoparticles have been studied as depending on the amounts of added water; chloroform; and an anionic surfactant, sodium bis(2-ethylhexyl)sulfosuccinate (AOT). It has been shown that, for different surfactants, AOT should be introduced in different ways to provide the nanoparticles with the electrokinetic potential values sufficient for enhancing their stability and ensuring the possibility of concentrating them by nonaqueous electrophoresis. In the case of Brij 30, it is preferable to introduce AOT after the synthesis as a “charging additive,” while, in the case of Tergitol NP-4, it should be added as a cosurfactant at the stage of the synthesis. The nanoparticles synthesized in Span 80 micelles have a rather high electrokinetic potential even in the absence of the additives. In this case, the use of AOT as a cosurfactant decreases the electrokinetic potential of the nanoparticles, while, being added after the synthesis, it increases the potential.