Self-Assembly and Property of Perfluoropolyether Derivatives Lubricating Films on Glass Surface

Two perfluoropolyether derivatives of different molecular weights were assembled on the glass surface using self-assembly technique. The chemical structure, wettability, microstructure and film thickness of the self-assembled lubricating film were measured by Fourier transform infrared spectroscopy (FT-IR), contact angle measuring instrument, atomic force microscopy (AFM) and ellipsometry. Furthermore, the friction properties of self-assembled and non-self-assembled two-perfluoropolyether derivative lubricating films were characterized by a TRB friction tester. Results show that the friction coefficient of the glass substrate was significantly reduced when perfluoropolyether derivatives were self-assembled on the glass surface. The molecular weight and the concentration of the self-assembled solution had an obvious influence on the wettability and wear resistance of the lubricating film. In addition, the self-assembled molecules had strong chemical bonding force with the glass substrate. The dense self-assembled lubricating film was obtained after heat treatment, resulting in better tribological property. The morphology of wear scar on the glass surface and the surface morphology, elemental composition and chemical state of the worn surface for the steel balls were analyzed by the 3D profiler, scanning electron microscope (SEM), X-ray energy spectrometer (EDS) and X-ray photoelectron spectroscopy (XPS). The results indicate that the perfluoropolyether derivatives film was decomposed during the friction process and the organic oxyfluoride and organic fluorocarbon was formed, transferring to the steel ball and inducing friction failure.