Extending LaMer's mechanism using open system for increasing forced and controlled growth of Au nano particles: Desired decreasing Fe3O4 nano particles size during simultaneous synthesis in optimized conditions

Abstract

The most effective parameters were found to obtain Au/Fe3O4 nano particles (NPs)-oleylamine composite. Having Au NPs with the controlled maximum mean size under the forced conditions was the main aim of this study. We used the continuous flow rates of oleylamine 75% to produce Au NPs under an open system by extended LaMer mechanisms. This process decreased the mean size of Fe3O4 NPs synthesized simultaneously, by classic LaMer mechanism. The Fe3O4 NPs production was carried out without continuous adding of any iron reactant, viz. as a closed system. In the absence of gold ions, the mean size of the synthesized Fe3O4 NPs using 2.5ml/min oleylamine was about 35.0nm at 2.0±0.5 °C after 120min. This mean size was decreased to 27.2, 21.4, 16.8 and 8.7nm, when Au NPs were simultaneous prepared using 0.5, 0.75, 1.5 and 2.5ml/min of oleylamine, respectively, at the same conditions. Surface Plasmon Resonance (SPR) adsorption was used to evaluate Au NPs production at first 30min, while Small Angle X-ray Scattering (SAXS) method was used to monitor the reaction progression for near-real time analysis of increasing the growth of Au NPs up to 280min, at the optimum conditions. Changing the properties of Fe3O4 NPs during processes was determined by studying Magnetization, Potentiometric titration, Inductive heating and Zeta potential.