A facile synthesis of high antibacterial polymer nanocomposite containing uniformly dispersed silver nanoparticles

Microemulsion technology is a typical method to prepare relatively stable silver nanoparticles (AgNPs) with desired microstructure. However, once out of microemulsion and filled into polymer material matrix, AgNPs are always hard to prevent from large aggregations. Therefore, mixed monomer methyl methacrylate (MMA)/styrene (St) and sodium citrate were chosen as continuous phase and reductant, respectively, to prepare a stable reversed microemulsion, in which AgNP colloids were in situ formed. The obtained microemulsion containing AgNPs was dispersed into water to form an ordinary emulsion, and the ordinary emulsion copolymerization was carried out to prepare poly(MMA-co-St)/Ag nanocomposite. Results of transmission electron microscopy (TEM) and X-ray diffraction (XRD) measurement show that spherical AgNPs disperse into the copolymer matrix evenly with an average diameter less than 10 nm. The UV-Vis diffuse reflectance spectroscopy reveals the typical emission peak of AgNPs at 410 similar to 430 nm. Analyses of Fourier transform infrared spectroscopy (FTIR) show a strong interaction between AgNPs and copolymer matrix. Thermogravimetric-differential scanning measurement shows that the decomposition temperature of poly(MMA-co-St) raises to a higher temperature in the presence of AgNPs. Antimicrobial assays of as-synthesized AgNPs and poly(MMA-co-St)/Ag nanocomposite prove their excellent antimicrobial activities.