Macromolecular tools for deposition of metallic nanoparticles on surfaces

A method is presented for generating quasi regular arrays of nanometer sized noble metal and metal oxide clusters on flat substrates by the use of a polymer template. The approach is of general applicability to other metals and various oxides. In the first step, polymeric micelles with a polar core were generated by dissolution of poly(strene)-block-poly(2-vinylpyridine) in toluene. These micelles were used as nanocompartments that were loaded with a defined amount of a metal precursor. The metal ions can be reduced in such a way that exactly one elemental particle is formed in each micelle, where each particle is of equal size. By dipping a flat substrate into a dilute solution, a monolayer of the micelles was obtained whereby the embedded equally large particles became arranged in a mesoscopic quasi hexagonal 2-D lattice. Exposure to an oxygen plasma allowed to remove the polymer completely leaving back the naked metal particles firmly attached to the substrate in the same quasi-hexagonal order as in the mono micellar film. The size (height) of the clusters could be varied between 1 nm and 15 nm depending on the concentration of the metal salt. The interparticle distance could be varied between 30 nm and 140nm by employing block copolymers with different length of the blocks.