(163p) Effect of Salt on Gold Nanoparticles Formation in Peo-Ppo-Peo Block Copolymer Solutions
Gold nanoparticles attract lots of research attention owing to their size-related electronic, magnetic and optical properties. This work reported the effect of salt on gold nanoparticles formation in poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Pluronic) aqueous solutions. Without addition of salt during the reaction, the resulted gold nanoparticles tend to aggregate into irregular shapes such as triangular, hexagonal and rod-like. Spherical nanoparticles with a narrow size distribution can only be obtained at high Pluronic concentration. The presence of a small amount of NaF salt in the synthesis significantly modified the quality of the gold nanoparticles. By adding NaF, Spherical and uniform gold nanoparticles (10nm) were obtained even at low Pluronic concentration. In addition, the color of the colloidal solution changed to red from purple, the gold surface plasma resonance (SPR) in UV spectra shift to 530 nm from longer wavelength, and the colloidal solution become more stable in long-term storage. The mechanism was attributed to the increase in the hydrophobicity inside Pluronic micelles after salt addition, which was more favorable for the entrapment of initial gold seeds in micelles and efficient stabilization of gold nanoparticles. This method provides a simple yet efficient method to improve the state of dispersion, stability and morphology of gold nanoparticles.