Molecular dynamics
The molecular propellers designed in the group of Prof. Petr Král from the University of Illinois at Chicago have their blades formed by planar aromatic molecules and the shaft is a carbon nanotube. Molecular dynamics simulations show that these propellers can serve as efficient pumps in the bulk and at the surfaces of liquids. Their pumping efficiency depends on the chemistry of the interface between the blades and the liquid. For example, if the blades are hydrophobic, water molecules do not bind to them, and the propellers can pump them well. If the blades are hydrophilic, water molecules form hydrogen bonds with the atoms in the polar blades. This can largely block the flow of other water molecules around the blades and significantly slow down their pumping.