Patterned Growth of Well-Aligned Carbon Nanotubes:  A Soft-Lithographic Approach

Using microcontact printing (μCP) and micromolding techniques, we have prepared micropatterns of carbon nanotubes aligned in a direction normal to the substrate surface. While the μCP process involves the region-specific transfer of self-assembling monolayers (SAMs) of alkylsiloxane onto a quartz substrate and subsequent adsorption of polymer chains in the SAM-free regions, the micromolding method allows the formation of polymer patterns through solvent evaporation from a precoated thin layer of polymer solution confined between a quartz plate and a poly(dimethylsiloxane) (PDMS) elastomer mold. The polymer patterns formed in both cases were then carbonized into carbon black for region-specific growth of the aligned nanotubes in the polymer-free regions by pyrolysis of iron(II) phthalocyanine (FePc) under Ar/H2 atmosphere at 800−1100 °C. Micropatterns of aligned nanotubes thus prepared have resolutions down to 0.8 μm, suitable for fabrication of various electronic and photonic devices.