Polymeric Friction Modifiers: Influence of Anchoring Chemistry on Their Adsorption and Effectiveness.

Correlated adsorption and lubricity have been investigated using polymeric friction modifiers, specifically designed with an oleophilic brush-forming block and an anchoring block of comparable length. Through adsorption, rheology, and friction measurements, we have highlighted the existence of boundary layers, whose molecular organization and mechanical properties govern the frictional behavior. We have demonstrated that changing the anchoring chemistry controls the final ordering in the boundary layer. The stability of the surface anchoring governs the onset of repulsion between the polymer layers and the capacity of the layer to withstand shear. The higher degree of molecular order provided by the most firmly anchored polymer to the surface was thereby responsible for the significant friction reduction observed.