The spreading behaviour of thin liquid polymer perfluoropolyethers on hard disc surface was investigated theoretically. The impact of slip at the boundary was taken into consideration. The diffusion coefficient Ds(h) was modified by incorporating the effective Knudsen number and molecular weight. It is found that slip has to be negative to ensure a maximum value of Ds(h) at lubricant thickness of 1 nm. Replenishment behaviour was also investigated and it was shown that a positive slip would quicken the lubricant movement, whereas a negative slip would slow down the replenishment. Finally, the spreading profiles were examined to investigate lubricant mobility.
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