Preparation of hydrophobic gold nanoparticles with safe organic solvents by microwave irradiation method

A safe organic solvent mixture n-heptane/ethanol was used as dispersion medium in reversal micelle to replace the commonly used toxic and highly volatile organic solvent such as chloroform and other solvents. This method overcame the obstacle for preparing hydrophobic nanoparticles by microwave irradiation method. The hydrophobic gold nanoparticles capped with octadecylamine (C18NH2) were prepared by using ethanol reduction in reverse micelle through microwave dielectric heating. The shape of obtained Au nanoparticles is nearly spherical and the size of them is sharply distributed in the 3-6 nm range, where 97% of the whole particles are included. The average diameter is determined to be 4.46 nm and the standard deviation is 0.44 nm. In addition to that, those particles obtained by this method could readily form the self-assembly two-dimensional arrangement on the water or membrane surface.