Properties of nanosilver coatings on polymethyl methacrylate

Elemental silver particles were prepared by the reduction of silver nitrate in ethanol in the presence of poly( N -vinyl-2-pyrrolidone), poly( N -vinyl-2-pyrrolidone)-co-polyvinyl acetate or poly( N -vinyl-2-pyrrolidone)-co-polyvinyl alcohol as stabilizing agent. Transmission electron microscopy (TEM) investigations reveal that in all cases spherical silver particles are obtained. Using poly( N -vinyl-2-pyrrolidone) or poly( N -vinyl-2-pyrrolidone)-co-polyvinyl alcohol as stabilizer, the average diameter of the silver particles is around 20 nm, and the degree of aggregation is low. That means these polymers are good stabilizers for silver particles. In contrast to that, in the presence of poly( N -vinyl-2-pyrrolidone)-co-polyvinyl acetate, heavily aggregated silver particles are formed. The good film-forming properties of the stabilizers were exploited to prepare coatings onto polymethylmethacrylate sheets using the silver dispersions. The optical as well as the silver ion release properties of the silver coatings were investigated. As expected, the wavelength of the surface plasmon resonance absorption shows a bathochromic shift with increasing mean diameter of the silver particles. The amount of silver ions released from these coatings as well as the kinetics of silver ion release depend on the polymer used as stabilizer for the silver particles. Silver ion diffusion processes govern the silver ion release kinetics from coatings consisting of silver nanoparticles and poly( N -vinyl-2-pyrrolidone) or poly( N -vinyl-2-pyrrolidone)-co-polyvinyl alcohol.