Low Friction Achieved Using Repulsive Van Der Waals Forces: A Nanotribology Study With Colloid Probe AFM

We show that extremely low friction can be achieved with the use of a divergent, pre-contact “surface force” — the repulsive, so called van der Waals force. In almost all cases this force is attractive, but for certain combinations of materials it manifests repulsively and at short separations (of the order of molecular distances) the load bearing capacity provided by the force is large. We have used the Atomic Force Microscope (AFM) in colloid probe mode to measure the friction between sub-microscopic contacts in the presence of such a force and have achieved a friction coefficient of the order of 0.0002.