Role of Configuration Entropy in Boundary Lubricants Based on the n-Perfluoropropylene Oxide Main Chain Structure

We have investigated the resistance of a novel end-functionalized perfluoropolyether (PFPE) lubricant film to slider-disk interactions caused by low-flying sliders. The PFPE lubricant is based on the CF₂CF₂CF₂O main chain monomer unit. Both slider-disk interactions and the formation of lubricant moguls are significantly reduced compared to the Fomblin Z backbone, (CF₂O) p -(CF₂CF₂O) q . These results are interpreted on the basis of ab initio quantum chemical computations that show that the barrier to internal rotation about the C-O bond in the CF₂CF₂CF₂O monomer unit is significantly larger than in the CF₂O monomer unit that is bordered by another CF₂O monomer unit, ~8 kcal/mol compared to