By measuring force-distance curves with an environmental scanning probe microscope, we quantitatively evaluated the effect of ultraviolet (UV) irradiation on adhesive properties of 2-nm-thick perfluoropolyether (PFPE) Z03 films. As bonding ratio increased with UV irradiation, adhesive force of the PFPE Z03 films initially decreased, but then increased after reaching a minimum at the bonding ratio of about 0.6. This is possibly attributed to the increase of meniscus force caused by decreased mobile lubricant thickness, and the decrease of van der Waals force between two solid surfaces caused by increased bonded lubricant thickness.
