Abstract
We present a neutron reflectivity study on the interface of flowing hexadecane, which is
known to exhibit surface slip on functionalized solid surfaces. The single crystalline silicon
substrates are either chemically cleaned or covered by octadecyl-trichlorosilane (OTS) which
result in different interfacial energies in respect to hexadecane. The liquid is in situ sheared
and the reflectivities are compared to the static case. Moreover, the temperature dependence
is recorded. For both types of interface, density depleted layers are observed, but shear affects them differently. Whereas at the attractive surface the depletion is enhanced by shear, the low
interfacial energy leads to a diminishment of the depleted layer when applying shear. This
systematic change of the depletion layer indicates different structural rearrangements under
shear load. Finally, the possible link of the depletion layer with surface slip is discussed.
