Nonlinear Frictional Energy Dissipation between Silica-Adsorbed Surfactant Micelles.

The origin of energy dissipation underlies all friction processes, which is crucial in the design of extremely low friction and wear systems. Amontons's friction law shows that the frictional energy dissipation should be linear with load because of the constant friction coefficient. However, in this Letter, we present the nonlinear behavior of frictional energy dissipation in boundary lubrication with silica-adsorbed surfactant micelles. There exist two completely different friction regimes: a near-zero friction regime with very little energy dissipation and a nonlinear friction regime with a great deal of extra energy dissipation. The additional energy dissipation presents a square (nonlinear) relation with applied load, originating from the elastic deformation of the adsorbed micelle layer on the two friction surfaces, which is tightly linked to the stiffness of the micelle layer and the diameter of the contact area.