Formation of close-packed silver nanoparticle multilayers from electrostatically grown octadecylamine/colloid nanocomposite precursors

The formation of close-packed silver nanoparticle thin films via a two-stag e self-assembly approach is described. In the first step, surface-modified silver colloidal particles are extracted from aqueous solution via electros tatic interactions into thermally evaporated fatty amine films. Thereafter, the excess fatty amine molecules in the organic matrix are removed by diss olution in a range of organic solvents of varying dielectric properties. Th ermogravimetric and quartz crystal microgravimetric studies indicate that, irrespective of whether the dissolution medium is polar or nonpolar, except for a monolayer of amine molecules in direct contact with the colloidal pa rticle surface, almost complete fatty amine dissolution occurs leading to a considerable increase in the packing density of the silver colloidal parti cles. While UV-vis spectroscopy measurements of the films after amine remov al suggest subtle differences in the final structure of the films prepared from the different solvents, atomic force microscopy studies show fairly ag gregated colloidal particle structures in all cases.