Surface films of silver nanoparticles for new liquid mirrors

Surface films of organically coated silver nanoparticles, when supported by a liquid substrate, exhibit properties of interest for the fabrication of a new class of liquid mirrors. The development of such mirrors clearly requires the optimization of film reflectivity and stability. The present article reports the dependence of film reflectivity on the choice and concentration of the organic ligand employed to protect against particle coalescence. In the specific case of the aromatic amines considered in this study, the choice of ligand is found to have little effect on the resulting optical properties of the films. Each ligand is, however, found to have an optimal concentration to be employed during particle coating. Characterisation of the films by thermogravimetry, elemental analysis and atomic adsorption measurements indicates a very high silver content, reaching about 98% by weight. X-ray photoelectron spectra reveal that the remaining organic component consists primarily of the stabilising ligand. The unexpectedly high silver content of these films eliminates the optimization of this parameter as a possible route to improved reflectivity.