Accordion-like plasmonic silver nanorod array exhibiting multiple electromagnetic responses

Abstract

We prepared a high-density array of "accordion-like" plasmonic silver nanorods over a large area (2.5 x 2.5 cm(2)) that exhibited multiple electromagnetic responses to visible and near-infrared (NIR) wavelengths. This array of "accordion-like" silver nanorods was fabricated by confining the lamellae-forming polystyrene-block-poly (methyl methacrylate) copolymer (PS-b-PMMA) inside the cylindrical pores of an aluminum oxide (AAO) template grafted with thin neutral brush layers. PS and PMMA lamellar nanodomains with sizes of 15 nm were alternatively stacked along the nanorod direction. After the AAO template was removed, a 5-nm-thick layer of silver was thermally deposited on only the PS nanodomains. Owing to the multiple resonances exhibited in the visible and NIR regimes, the array could be used for multi-analyte detection. Furthermore, this concept of fabricating sophisticated nanoscale architectures by utilizing block copolymer self-assembly and incorporating plasmonic metals into one nanodomain could be applied to realize large-scale metamaterials that function under visible and NIR wavelengths.