The Design of Boundary Film-Forming PMA Viscosity Modifiers

Previous research has shown that some viscosity modifier additives are able to adsorb from oil solution on to metal surfaces to produce thick, viscous boundary films. These films enhance lubricant film formation in slow-speed and high temperature conditions and thus produce a significant reduction in friction. This article describes a systematic study of this phenomenon, which makes use of the versatile nature of polymethacrylate (PMA) chemistry. Dispersant polymethacrylates with a range of different functionalities, molecular weights, and architectures have been synthesized using controlled radical polymerization techniques. The influence of each of these features on boundary film formation and friction has been explored using optical interferometry and friction versusspeed measurement. From the results, guidelines have been developed for designing PMAs having optimal boundary lubricating and, thus, friction-reducing properties.

Keywords: Elastohydrodynamic Lubrication, Boundary Lubrication, Additive, Viscosity Index Improver, Polymethacrylate, Friction