  Using equilibrium and non-equilibrium molecular dynamic (MD) simulations, we
found that engineering the strain on the graphene planes forming a channel can
drastically change the interfacial friction of water transport through it.
There is a sixfold change of interfacial friction stress when the strain
changes from -10% to 10%. Stretching the graphene walls increases the
interfacial shear stress, while compressing the graphene walls reduces it.
Detailed analysis of the molecular structure reveals the essential roles of the
interfacial potential energy barrier and the structural commensurateness
between the solid walls and the first water layer. Our results suggest that the
strain engineering is an effective way of controlling the water transport
inside nano-channels. The resulting quantitative relations between shear stress
and slip velocity and the understanding of the molecular mechanisms will be
invaluable in designing graphene nano-channel devices.
