Preparation of superhydrophobic nanodiamond and cubic boron nitride films

Superhydrophobic surfaces were achieved on the hardest and the second hardest materials, diamond and cubic boron nitride (cBN) films. Various surface nanostructures of nanocrystalline diamond (ND) and cBN films were constructed by carrying out bias-assisted reactive ion etching in hydrogen/argon plasmas; and it is shown that surface nanostructuring may enhance dramatically the hydrophobicity of ND and cBN films. Together with surface fluorination, superhydrophobic ND and cBN surfaces with a contact angle greater than 150 degrees and a sliding angle smaller than 10 degrees were demonstrated. The origin of hydrophobicity enhancement is discussed based on the Cassie model. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3494269]