Catalytically Active Metal Nanomeshes Fabricated by Block Copolymer Self-Assembly on Unidirectionally Aligned Soft Topographic Patterns

In this study, we demonstrate extremely aligned one-dimensional (1D) nanostructures in a large area by using a directed self-assembly (DSA) of block copolymers (BCPs) in thin films on unique topographic patterns of poly(tetrafluoroethylene) (PTFE). Unidirectionally aligned PTFE patterns are first fabricated by physically rubbing a PTFE block on a flat Si surface at high temperatures close to its melting points (Tm). The thin films of cylinder-forming polystyrene-block-poly(2-vinylpyridine) copolymers (S2VPs) are spin-coated directly on the PTFE patterns, followed by a solvent-annealing process to induce their directed self-assembly. During solvent-annealing, the PTFE patterns guide the cylinders of P2VP blocks to orient parallel to the surface and align extremely in a large area. Interestingly, it is also found that the alignment of the cylinders in BCP thin films is strongly dependent on the relation between the periodic length of cylinders and dimension of the soft PTFE patterns. In addition, the P2VP cylinders are utilized as effective templates to generate 1D metal nanostructures. By depositing self-assembled BCP films on top of the nanostructures, followed by sequential metallization, unique metal nanomesh structures are also generated. Finally, these metal nanostructures are used to investigate their catalytic effect for the chemical reduction of 4-nitrophenol.