Silver ion release from polymethyl methacrylate silver nanocomposites

Polymethyl methacrylate (PMMA) silver nanocomposites were prepared by the thermal reduction of silver(I) trifluoroacetate. Transmission electron microscopic investigations reveal that the silver nanoparticles were spherical and their particle sizes were between 5 nm and 50 nm. The particles were distributed randomly in the PMMA matrix. Immersion of the nanocomposites in water led to a release of silver ions. The silver ion release from the PMMA silver nanocomposites was measured by anodic stripping voltammetry. When a nanocomposite sample having a surface area of 36.8 cm(2) and a silver content of 0.12 wt% was immersed in water, the silver ion concentration in the surrounding water was about 0.05 mg/l after two days. This is sufficient to kill bacteria. Using conventional silver powder as a filler, a silver content 30 times higher is necessary to achieve the same silver ion concentration in the surrounding water under the same conditions. The silver ion concentration in the water increased with increasing nanosilver content of the composites. The composites incorporating conventional silver powder are not transparent. In contrast, PMMA silver nanocomposites containing less than 0.25 wt% silver show a translucency sufficient for use in packaging materials.