The dynamic behavior of thin-film lubricants

The dynamic behavior of thin perfluoropolyether (PFPE) films is critically reviewed. A methodology for extracting spreading information from scanning microellipsometry (SME) experiments to investigate the replenishment characteristics of various PFPEs on silica and carbon surfaces is presented. Furthermore, the relationship among SME measurements, surface energy (or disjoining pressure), rheology, and tribology is discussed. Maxwell's equal area construction is introduced into the disjoining pressure-height isotherm to correlate surface energy with the SME profile. There is a qualitative correlation at small height (h), which becomes inconsistent as h becomes large, Examples with hydrogenated and nitrogenated carbon overcoat films are used to illustrate this point.