Molecular effects on boundary condition in micronanoliquid flows.

We experimentally investigated molecular effects of the slipno-slip boundary condition of Newtonian liquids in micro- and nanochannels as small as 350 nm. The slip was measurable for channels smaller than approximately 2 mum. The amount of slip is found to be independent of the channel size, but is a function of the shear rate, the type of liquid (polar or nonpolar molecular structure), and the morphology of the solid surface (molecular-level smoothness).