Roll-to-roll nanoimprint lithography using a seamless cylindrical mold nanopatterned with a high-speed mastering process.

The advanced optical and wetting properties of metamaterials, plasmonic structures, and nanostructured surfaces have been repeatedly demonstrated in lab-scale experiments. Extending these exciting discoveries to large-area surfaces can transform technologies ranging from solar energy and virtual reality to biosensors and anti-microbial surfaces. Although photolithography is ideal for nanopatterning of small, expensive items such as computer chips, nanopatterning of large-area surfaces is virtually impossible with traditional lithographic techniques due to their exceptionally slow patterning rates and high costs. This article presents a high-throughput process that achieves large-area nanopatterning by combining roll-to-roll (R2R) nanoimprint lithography (NIL) and nanocoining, a process that can seamlessly nanopattern around a cylinder hundreds of times faster than electron-beam lithography. Here, nanocoining is used to fabricate a cylindrical mold with nanofeatures spaced by 600 nm and microfeatures spaced by 2 µm. This cylindrical drum mold is then used on a R2R NIL setup to pattern over 60 feet of polymer film. Microscopy is used to compare the feature shapes throughout the process. This scalable process offers the potential to transfer exciting lab-scale demonstrations to industrial-scale manufacturing without the prohibitively high cost usually associated with the fabrication of a master mold.

Deposition of Ni nanoparticles onto porous supports using supercritical CO2: effect of the precursor and reduction methodology.

The deposition of Ni nanoparticles into porous supports is very important in catalysis. In this paper, we explore the use of supercritical CO(2) (scCO(2)) as a green solvent to deposit Ni nanoparticles on mesoporous SiO2 SBA-15 and a carbon xerogel. The good transport properties of scCO(2) allowed the efficient penetration of metal precursors dissolved in scCO(2) within the pores of the support without damaging its structure. Nickel hexafluoroacetylacetonate hydrate, nickel acetylacetonate, bis(cyclopentadienyl)nickel, Ni(NO(3))2⋅6H(2)O and NiCl(2)⋅6H(2)O were tried as precursors. Different methodologies were used: impregnation in scCO(2) and reduction in H(2)/N(2) at 400°C and low pressure, reactive deposition using H(2) at 200-250°C in scCO(2) and reactive deposition using ethanol at 150-200°C in scCO(2). The effect of precursor and methodology on the nickel particle size and the material homogeneity (on the different substrates) was analysed. This technology offers many opportunities in the preparation of metal-nanostructured materials.