PEG-coated silver nanoparticles by ultrasound assisted colloidal synthesis

Abstract

Ultrasound assisted colloidal synthesis is one of the simplest and inexpensive methods for AgNPs preparation. In this work, we use this method to synthesize small size AgNPs using PEG as stabilizer and citric acid as reducer. The alkalinity effect of NaOH to pH control and silver oxidation limitation was studied. Also, PEG concentration and [citric acid]/[AgNO3] molar ratio effect in size distribution was analyzed finding the significant parameters to control to achieve small size AgNPs. Theorical calculations of surface plasmon resonance were made over UV-Vis characterizations to obtain size diameter. Finally, growth phases of AgNPs were visualized by UV-Vis characterization and size distribution was obtained by the data collected in TEM characterization. SPR bands of the smallest AgNPs synthetized were located at 396 nm which defines the size of the spherical nanoparticle by theorical calculation less than 10 nm. The mean size obtained by TEM micrographs was 2.61 nm and Ag and PEG hydroxyl groups interaction was detected by 418 cm-1 FTIR band.