Tribological Behavior of Terphenyl Self-Assembled Monolayer Studied by a Pin-on-Plate Method and Friction Force Microscopy

Abstract

We investigated the friction properties of organic self-assembled monolayers (SAMs) using a pin-on-plate method, friction force microscopy (FFM) and X-ray photoelectron spectroscopy (XPS). A pin-on-plate tribometer was used for friction measurements under practical conditions. The sliding speed and load in the pin-on-plate method were higher than those of conventional FFM. Although the friction coefficients of terphenyl methane thiol SAMs measured by FFM were higher than those of soft octadecanethiol (ODT) SAMs, the friction coefficients of both the SAMs measured by the pin-on-plate method showed almost the same values. In the case of pin-on-plate measurements, the deformation of substrates may affect the friction behavior arising from the higher sliding speed in the pin-on-plate method. Furthermore, XPS measurements indicated that TP1 SAM has a higher durability against friction than ODT SAM. Therefore, we believe that terphenyl methane thiol SAM is a good candidate for a typical future lubricant.