Superhydrophobicity of boron nitride nanotubes grown on silicon substrates.

Partially vertical aligned boron nitride nanotubes (BNNTs) on Si substrates are found to be superhydrophobic in contrast to boron nitride (BN) thin films. While the hexagonal-phase BN films are partially wetted by water with advancing contact angle of about 50 degrees , partially vertically aligned BNNTs can achieve superhydrophobic state with advancing water contact angle exceeding 150 degrees . Our results show that the pH value of water does not affect the wetting characteristics of BNNTs. Since BN is chemically inert, resistive to oxidation up to 900 degrees C, and transparent to visible-UV light, BNNTs could potentially be useful as self-cleaning, transparent, insulating, anticorrosive coatings under rigorous chemical and thermal conditions.