A perfectly hydrophobic surface (thetaA/thetaR = 180 degrees /180 degrees)

A perfectly hydrophobic surface with both advancing and receding water contact angles of 180 degrees was prepared using a facile method on a silicon wafer. Phase separation of a toluene-swollen covalently attached methylsilicone results in a nanoscale network structure that is responsible for the superhydrophobicity. A method for testing extreme hydrophobicity was devised to distinguish between surfaces exhibiting contact angles of 180 and 179 degrees .