General approach for fabricating nanoparticle arrays via patterned block copolymer nanoreactors

A general approach to fabricate nanoparticle arrays of different kinds of materials is demonstrated in this paper. It was found that the center-to-center distance of the nanoparticles or the nanoclusters can be controlled using patterned block copolymer nanoreactors by adding polystyrene (PS) homopolymer to poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer thin film. The number of the nanoparticles formed in the P4VP nanodomains can also be adjusted by addition of polystyrene (PS) homopolymer to poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) diblock copolymer. In fabrication of Au nanoparticle arrays, HAuCl₄ precursor was directly loaded into P4VP nanodomains of the diblock copolymer thin film by using a methanol solvent, which is a good solvent for P4VP but non-solvent for PS. The Au nanoparticle arrays were then obtained by reducing HAuCl₄ with sodium citrate dihydrate, and then in situ transferred to silicon substrate by a two-step calcination method. ZnO and Fe _x O _y nanoparticle arrays were also synthesized by this approach with thermal decomposition and double decomposition reactions, respectively. Additionally, the advantage of using two-step calcination method over the air plasma method was discussed.