Sliding friction with polymer brushes.
Using high-resolution shear force measurements, we examine in detail the frictional drag between rubbing surfaces bearing end-tethered polymeric surfactants (brushes). The drag attains a maximum on initial motion, attributed to elastic stretching of the chains, which falls by a cascade of relaxations to a value characteristic of kinetic friction. This has a very weak velocity dependence, attributed to chain moieties dragging within a self-regulating, mutual interpenetration zone. When sliding stops, the shear stress across the polymer layers decays logarithmically with time, consistent with the relaxation of a network of dangling ends.
Tadmor
Rafael
R
Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100, Israel.
Janik
Joanna
J
Klein
Jacob
J
Fetters
Lewis J
LJ