Carbon Nanopatterns and Nanoribbons From Directly Nanoimprinted Polyacrylonitrile: Correlation Between Crystallite Orientation and Nanoimprint Process

The ability to create carbon nanostructures such as carbon nanofibers (CNF) and patterns with controlled dimensions, position and ordering, is crucial for engineering all-carbon devices. We present the fabrication of lithographically defined carbon patterns and nanoribbons using a common carbon precursor, polyacrylonitrile (PAN). Thermal-embossing NIL (TE-NIL) is used to directly fabricate PAN films that can be subsequently cyclized and carbonized to yield highly uniform carbon patterns and nanoribbons over a large area. We demonstrate that this technique is reliable and capable of nanofabrication over a large surface area at low cost, compared with current carbon-patterning techniques. The evolution of the nanostructures during heat treatment was studied. Most interestingly, the deformation profile of the PAN during the imprinting process resulted in a distribution of aligned PAN chains within the patterns, which led to a similar anisotropic correlation of the carbon crystallites in the carbonized structures.