The hydrophobic gold nanoparticles were fabricated through n-butanol reduction in situ under microwave irradiation by using p-dodecyloxybenzenmethanamine (C₁₂OBA)/n-butanol/n-heptane/HAuCl₄/ NaOH(aq.) W/O microemulsion as a microreactor. The C₁₂OBA-stabilized gold nanoparticles were characterized by UV-vis, TEM, XRD, FT-IR and CA (contact angle), respectively. The results showed that C₁₂OBA, a novel surfactant, could not only take part in the formation of a stable W/O microemulsion, but also be used as a good protecting reagent for gold nanoparticles. The increase of alkalinity within the inner-core of microemulsion enhanced the reducing ability of n-butanol located in the membrane phase. As the amount of HAuCl₄ was fixed, the increase of molar ratios of C₁₂OBA/gold was beneficial to obtain hydrophobic gold nanoparticles with small-size and higher monodispersity; while the increase of polarity of reaction system led to the increase of size and decline of monodispersity of particles. And thus by this method, the hydrophobic gold nanoparticles with about 5 nm-diameter and high monodispersity could be easily and quickly synthesized.

Key words: p-dodecyloxybenzenmethanamine, hydrophobic gold nanoparticle, W/O microemulsion, in situ reduction, microwave irradiation