Infusion of silver nanoparticles into transparent plastics using supercritical carbon dioxide

Supercritical fluid infusion was carried out to develop eye protection lenses by dispersing silver nanoparticles beneath the lens surfaces. Supercritical carbon dioxide and 10 mol% acetone were employed as the processing media. The lenses were made of diethylen glycol his (allyl carbonate) resin (CR39). The metal precursor of silver acethylacetonate (Ag (acac)) was infused into CR39 at 90 degrees C and 25 MPa in 2 hours. Silver nanoparticles of 3-8 nm were formed by reducing the silver precursor at 110 degrees C, 0.1 MPa for 2 h. The produced silver nanoparticles were mainly distributed within the surface layer of about I urn thickness, while the density of silver particles decreased sharply in deeper layers. When the reduction process was done at supercritical state, i.e., 25 MPa, silver particles having diameter of 5-20 nm were uniformly generated within a layer of about 100 mu m thickness. The particle size became a little larger (15-25 nm) on repeating the infusion and the thermal treatment. The lenses after the infusion treatment show yellow color and can cut off up to 90% of UV-A (315-380 nm) and Blue-light (380-500 nm) rays that are harmful to human eyes. The supercritical infusion methods were thus very effective for synthesis of functional materials of polymers.