A generic mechanism of sliding friction between charged soft surfaces.

A universal sliding friction mechanism between soft, electrically charged surfaces (e.g., those carrying polyelectrolytes) is proposed. The Coulomb field of the randomly distributed charges induces a damped motion of the charges of the opposite surface, which gives rise to dissipation, and thus to friction. It is predicted that this friction force, which diverges at zero separation, may overcome viscous friction at distances significantly exceeding the Bjerrum length. This is not only of fundamental interest, but also of potential importance in life science and many practical situations.