Placement Control of Nanomaterial Arrays on the Surface-Reconstructed Block Copolymer Thin Films

School of Chemical and Biological Engineering, Seoul National University, Seoul, 151-744, Korea.
ACS Nano (Impact Factor: 12.88). 11/2009; 3(12):3927-34. DOI: 10.1021/nn900914q
Source: PubMed


We present a control strategy for the facile placement of densely packed nanomaterial arrays (i.e., nanoparticles and nanorods) on surface reconstructed polystyrene-block-poly(methyl methacrylate) thin film patterns. The surface reconstruction of perpendicularly oriented block copolymer thin films, which were produced by a treatment with selective solvent vapors for both blocks, created the topographical nanopatterns with enough height contrast for nanoparticle deposition without the need for additional selective etching of a single block domain. The deposition method of nanomaterials was also optimized, and densely packed one- and two-dimensional nanomaterials arrays in the grooves of the block copolymer film patterns were fabricated efficiently. Then, we demonstrated that height contrast of the surface reconstructed block copolymer films could be reversed by electron beam irradiation resulting in nanomaterial arrays placed at the mesa phase of the nanopatterns. On the basis of this nanomaterial placement control strategy, dual nanomaterial arrays on a single block copolymer pattern were also realized.

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    • "It has been well known that some block copolymers can self-assemble into different nanopatterns when they are spin-coated as a thin film on a flat substrate. The unique patterns of such block copolymer thin films can be used as templates in fabricating various ordered nanoarrays (Lopes and Jaeger 2001; Ansari and Hamley 2003; Koh et al. 2007; Son et al. 2009; Li and Ober 2006; Morin et al. 2009; Tang et al. 2010). For example, densely packed, high aspect ratio nanopillar and nanohole SiO 2 structures, which can be used as nanoimprint molds, were fabricated by using vertically oriented cylindrical poly(styrene-b-methyl methacrylate) (PS-b-PMMA) block copolymer template (Park et al. 2009). "
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    ABSTRACT: 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. KeywordsNanoparticle array–Block copolymer–Nanoreactor–Patterning–Nanomanufacturing
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    ABSTRACT: The formation of well-oriented cylinders with perpendicular morphology for polystyrene-b-polydimethylsiloxane (PS-PDMS) thin films was achieved by spin coating. The self-assembled PS-PDMS nanostructured thin films were used as templates for nanopatterning; the PDMS blocks can be oxidized as silicon oxy carbide microdomains, whereas the PS blocks were degenerated by a simple oxygen plasma treatment for one-step oxidization. As a result, freestanding silicon oxy carbide thin films with hexagonally packed nanochannels were directly fabricated and used as masks for pattern transfer to underlying polymeric materials by oxygen reaction ion etching (RIE) to generate topographic nanopatterns. By taking advantage of robust property and high etching selectivity of the SiOC thin films under oxygen RIE, this nanoporous thin film can be used as an etch-resistant and reusable mask for pattern transfer to various polymeric materials. This approach demonstrates a simple, convenient, and cost-effective nanofabrication technique to create the topographic nanopatterns of polymeric materials.
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