Ordered Deposition of Inorganic Clusters from Micellar Block Copolymer Films

Abstract

A method is presented for generating quasiregular 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(styrene)-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 or oxidic 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 quasihexagonal two-dimensional (2-D) lattice. Exposure to an oxygen plasma allowed removal of the polymer completely, leaving the naked metal particles firmly attached to the substrate in the same quasihexagonal order as in the monomicellar film. A modified procedure in which the precursor salt was not reduced before the plasma treatment yielded clusters of identical size and in the same 2-D order. The size (height) of the clusters could be varied between 1 and 15 nm depending on the concentration of the metal salt. The interparticle distance could be varied between 30 and 140 nm by using block copolymers with different lengths of the blocks. Such lattices of Au particles have been used to bind streptavidin proteins in an ordered array.

Surface Patterning with Colloidal Monolayers

“…Me-containing micelles as sacrificial layer very fast very high (no lower limit) very low low [119] , [120] Non- very low high [121] Theory 41…”

“…[119] They used block-copolymer micelles of polystyrene-poly(2-vinylpyridine) that were charged with auric acid during the assembly process. After assembly into a two-dimensional crystal on a solid substrate, a plasma etching procedure was applied to remove the organic compounds and to reduce the auric acid to inorganic gold nanoparticles.…”

Induction of Cell Polarization and Migration by a Gradient of Nanoscale Variations in Adhesive Ligand Spacing

“…[21][22][23][24] Varying the molecular weight of diblock copolymers causes variations in lateral spacing between the gold nanoparticles. Here, we demonstrate that the lateral spacing of gold nanoparticles also depends on the concentration of the micellar dipcoating solution and on the substrate retraction velocity, the latter of which enables the formation of well-defined nanoparticle spacing gradients.…”

Directing the Self‐Assembly of Mesostructured Hybrid Materials: Effect of Polymer Concentration and Solvent Type

“…We found that the morphology of selfassembled thin films can be controlled much easier, if the precursor loaded material PS-b-P[4VP(HAuCl 4 )] (Step II) is used to deposit the films prior to the reduction step. Subsequently, different methods such as wet-chemical processes, [22] UV irradiation, [23] or O 2 -plasma etching [24] can be applied to generate Au-nanoparticles.…”