Directing Oleate Stabilized Nanosized Silver Colloids into Organic Phases

Abstract

Nanosized hydrophobic, oleate stabilized silver organosols in various organic solvents are obtained using a solvent exchange method. The silver particles are initially prepared as a hydrosol in the presence of sodium oleate (surfactant). Then a transfer of the colloid to an organic phase is induced by a low concentration of several agents such as orthophosphoric acid, with a transfer efficiency of 50−70%. The hydrophobic colloid is stable and the particles retain their integrity even after the solvent is evaporated and the dried deposit is resuspended in a variety of other solvents. We present the preparation method in detail and characterize the hydrosol and organosol particles by electron microscopy, electrophoresis, and UV−visible extinction spectroscopy. On the basis of IR spectroscopy we discuss the conformation of the surfactant adsorbed on the silver cores and the changes in it as the particles transfer into the organic environment.

Titania–silver and alumina–silver composite nanoparticles: Novel, versatile synthesis, reaction mechanism and potential antimicrobial application

“…It was concluded that Ag + ions coordinated to the relatively free -COOH groups, then Ag nanoparticles formed on the surface of the TiO 2 particles with the oleic acid acting as a linker between the titania and Ag nanoparticles. These conclusions are in agreement with previous reports, since oleic acid is a well-known capping agent for Ag nanoparticles [44][45][46]. Figure 5B showed a main peak at 531.2 eV which was identified as O from alumina.…”

“…Moreover, in addition to shifting the pH to 9.26, the Ag + ions were reduced due to addition of NaBH 4 . Thus it could be concluded that oleic acid coordinated with the Ag nanoparticles through its head groups, as oleic acid is a well-known capping agent for Ag nanoparticles [44][45][46]. No significant shift was observed in the region 3010-2850 cm -1 throughout the synthesis (cf.…”

“…A new peak was observed at 1522 cm-1, attributed to the formation of an Ag-oleate complex with the -COOH groups of the second layer of oleic acid (cf. Curve 4, Figure 6) [44][45][46].…”

“…Curve 4, Figure 4). This was considered evidence that Ag + ions were interacting with the -COOH groups of oleic acid to form an Ag-oleate complex [44][45][46]. The 1519 cm -1 peak remained following the reduction of Ag + complex with NaBH 4 (cf.…”

Nitrate and Nitrite Electrocatalytic Reduction at Layer-by-Layer Films Composed of Dawson-type Heteropolyanions Mono-substituted with Transitional Metal Ions and Silver Nanoparticles

“…This technique is based upon the electrostatic interaction between oppositely charged species from dilute solution [36][37][38]. Nanocomposite materials which are based on inorganic nanoparticles and polymers offer unique properties, such as, optical, magnetic, catalytic, thermal and electrochemical, which depend on particle size, shape, dimensions and surrounding environment [39][40][41][42][43]. The unusual properties of metallic nanoparticles are due to the collection of high energy surface atoms compared to the bulk solid material.…”