Photoresist Derived Electrospun Carbon Nanofibers with Tunable Morphology and Surface Properties

A new precursor, SU-8, which is a negative photoresist, was electrospun to produce ultrafine polymeric fibers with a wide range of morphology and wettability characteristics. Electrospun nanofibers of SU-8 were pyrolyzed at 1173 K in an inert atmosphere to give carbon nanofibers. A set of parameters, including electric potential, distance between source and collector, polymer flow rate, and polymer concentration, was optimized for high-viscosity SU-8 photoresist to synthesize long continuous carbon fibers having diameters in the range of 120-600 nm. However, for the same conditions, medium- and lower-viscosity SU-8 yielded beaded fibers and isolated beads, respectively. The wettability of the carbon web was significantly influenced by its surface morphology, as shown by water contact angle measurements. These SU-8-derived carbon nanostructures with tunable surface properties and morphologies could be especially suitable for integration with photoresist-based carbon-MEMS to produce multiscale hierarchal assemblies and could be of potential use in a broad range of applications.