Boundary Friction on Molecular Lubricants: Rolling Mode?

TL;DR

This paper introduces a theoretical model for low-temperature friction involving lubricant molecules between smooth surfaces, highlighting different energy dissipation modes like rocking and rolling, and their impact on friction behavior.

Contribution

It presents a novel theoretical framework accounting for lubricant deformations and rotations, explaining the transition between rocking and rolling modes of energy dissipation.

Findings

Friction force exhibits non-monotonic dependence on external load.

Different dissipation modes are associated with stick-and-slip behavior.

Rolling mode can dominate at slow surface displacements.

Abstract

A theoretical model is proposed for low temperature friction between two smooth rigid solid surfaces separated by lubricant molecules, admitting their deformations and rotations. Appearance of different modes of energy dissipation (by ''rocking'' or ''rolling'' of lubricants) at slow relative displacement of the surfaces is shown to be accompanied by the stick-and-slip features and reveals a non-monotonic (mean) friction force {\it vs} external load