Dipole-dependent slip of Newtonian liquids at smooth solid hydrophobic surfaces.

We present atomic force microscopy observations of the "effective" slippage of various nonpolar and polar liquids on alkylsilane coated glass surfaces. For small contact angle nonpolar liquids, the slip length decreases as one approaches a wetting transition. However, for large contact angle polar liquids it is found that the slip length is primarily influenced by the dipole moment, rather than the wettability of the liquid for the surface, where the slip length decreases with increasing dipole moment.