Noble metallic nanoparticles reduced by PS-based oligomers through one-step synthesis

Sulfate terminated oligomers based on polystyrene (PS), poly(styrene-co-methyl methacrylate) (PS-co-PMMA) and poly(methyl methacrylate) (PMMA) were prepared through free-radical polymerization based on styrene, methyl methacrylate/potassium persulfate/water system in the presence of carbon tetrabromide. The polydispersity of molecular weight of the resulting oligomers decreased with both conversion and MMA fraction in the feed, while number-averaged molecular weight (Mn) increased with conversion and MMA concentration in the monomer feed. These oligomers can reduce noble metal nanoparticles without external reducing agent and surfactant. The size and shape of noble metal nanoparticles can be tailored by changing the compositions of PS-co-PMMA which obtained by polymerizations at different MMA/St molar ratios. The nanoparticles were well-dispersed in water or acetone without surfactant and reductant in the mixture. Based on the Gaussian 98 program, the bonding energies of SO bonds of PS, PMMA and PS-co-PMMA were compared. The simulated results of Gaussian 98 program were in good agreement with the capabilities of these oligomers applied for one-step reduction of nanoparticles. The oligomers and their corresponding nanocomposites were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrum (FT-IR), X-ray power diffraction (XRD), UV–visible spectra, and Inductively Coupled Plasma-Atomic Emission Spectrometer (ICP-AES).