Intermolecular potentials and vapor–liquid phase equilibria of perfluorinated alkanes

We propose 2 sets of intermolecular potentials for a united atom model of linear perfluorinated alkanes in their fluid states. Configurational-bias Monte Carlo simulations in the Gibbs ensemble have been carried out to determine the vapor–liquid phase equilibria for CnF2n+2 with n=5, 6, 7, 8, 10 and 16. Both sets of parameters yield critical temperatures which are in excellent agreement with experiment data. However, the critical densities are slightly too high for one model and slightly too low for the other. The saturated liquid densities agree with experiment to better than 5%. Variations of the critical properties with chain length show the correct scaling for both models.