Calculation of Disjoining Pressure for Lubricant Films Via Molecular Simulation

Disjoining pressure of polymeric liquid films on solid wall and surface tension of the films suspended in vapor are examined via molecular dynamics simulations. The disjoining pressure is calculated from the augmented Young-Laplace equation, which is used to reproduce a fluid bridge between two walls in a simulation cell. Higher surface energy of the wall increases the disjoining pressure resulting in increased thickness of the plane film coexisting beside the fluid bridge. The simulations with the fluid bridge geometry are also used to qualitatively estimate the disjoining pressure of polymers with functional endgroups. It is shown that the strength of the functionality at endgroups does not affect the stability of the film