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

Abstract

The formation of close-packed silver nanoparticle thin films via a two-stage self-assembly approach is described. In the first step, surface-modified silver colloidal particles are extracted from aqueous solution via electrostatic interactions into thermally evaporated fatty amine films. Thereafter, the excess fatty amine molecules in the organic matrix are removed by dissolution in a range of organic solvents of varying dielectric properties. Thermogravimetric 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 particle surface, almost complete fatty amine dissolution occurs leading to a considerable increase in the packing density of the silver colloidal particles. While UV-vis spectroscopy measurements of the films after amine removal suggest subtle differences in the final structure of the films prepared from the different solvents, atomic force microscopy studies show fairly aggregated colloidal particle structures in all cases.