Depletion kinetics of perfluoropolyether films with functional end groups using molecular dynamics simulation

Molecular dynamics simulation coupled with a coarse-grained model is employed to investigate the surface depletion kinetics of functional polyether film under heat treatment. The real-time evolutions of lubricant film desorption and decomposition are examined during rapid heating and isothermal stages. The reaction order of lubricant depletion is evaluated during the rapid heating using a constant heating rate and various coverages. It reveals that a peak in the desorption (decomposition) rate is formed and is independent of the mass (bond) coverage, which gives rise to a first-order, coverage independent depletion kinetics. The rate constants for lubricant desorption and decomposition are thus calculated based on a first-order kinetics-controlled reaction during the isothermal stage. The kinetics of functional lubricant depletion shows that desorption is the main mechanism of lubricant depletion under rapid and isothermal heat treatment and is the major cause of lubricant thermal instability on the surface.