The surfaces of bulk carbon nanotubes compacted by plasma spark sintering have been modified with polytetrofluorethylene, thereby producing a super-hydrophobic surface with a contact angle above 160°. The surface roughness and air trapped in pores and between the polytetrofluorethylene particles are responsible for the super-hydrophobility. The material can be machined into desired shapes with fine and complex channels, allowing internal surfaces to also be super-hydrophobic.
Li, J., Wang, L., & Jiang, W. (2010). Super-hydrophobic surface of bulk carbon nanotubes compacted by spark plasma sintering followed by modification with polytetrofluorethylene. Carbon, 48(9), 2668-2671. https://doi.org/10.1016/j.carbon.2010.03.038