Chemically tunable nanoscale propellers of liquids.

We explore the limits of liquid pumping by "classical propellers" with molecular-scale blades. Our molecular dynamics simulations reveal a huge sensitivity of pumping to the chemistry of the blade-liquid interface. We demonstrate selective pumping of hydrophobic and hydrophilic liquids, where the pumping rate is determined by the effective profile of the solvated nanoscopic blades. These results have important implications for a potential design and assembly of molecular pumps and motile devices.