A molecularly thin perfluoropolyether (PFPE) lubricant film composed of bonded and mobile molecular layers was dip-coated on diamond-like carbon (DLC) surfaces, and experiments using a ball-on-disk tribotester were carried out to determine the durability characteristics of the thin lubricant film. The PFPE with two and four hydroxyl end groups were used for the formation of the bonded layer and the same species or the PFPE without the hydroxyl end group were used for the formation of the mobile layer. It was found that the lifetime of a nanolubricant film increased with an increase in the mobile-layer thickness, and that the mobile layer made of PFPE molecules without hydroxyl end groups was more effective in prolonging the lifetime compared to those with the hydroxyl end groups.
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