Effect of polyvinyl alcohol molecular weight and UV-photoactivation on the size of gold nanoparticle

The preparation and optical properties of gold nanoparticles prepared by the UV-photoactivation technique at two wavelengths (365 and 254 nm) at different irradiation times were studied. Polyvinyl alcohol two molecular weights (Mw=125,000 and 6000) was used as a radical surfactant stabilizer. The structure and optical properties were investigated by transmission electron microscopy (TEM) and ultraviolet–visible (UV–VIS) spectroscopy. The configuration of particles is rather spherical and exhibits narrow size distribution with mean diameter depending on the power of irradiation and the molecular weight of the surfactant stabilizer for all samples. The maximum bands appearing in the range (528–546 nm) are related to surface plasmon resonance (SPR). Red shift with broadening of (SPR) bands has been observed depending not only on UV-photoactivation but also on the molecular weight of the surfactant stabilizer. The absorption band at 308 nm could be attributed the electron transfer between the surfactant stabilizer and NaBH4 through the gold particles. This study presents a simple method for synthesis and control of the particle size of gold nanoparticles.