Molecular modeling of perfluoro compounds

Perfluoro compounds receive much attention due to their distinctive properties and multiple applications. Consequently, it would be of great interest to be able to model those applications with molecular simulation techniques. To achieve this goal, a realistic potential model is needed. For perfluoroalkanes, such a model has been developed and reported. However, for perfluoroethers, no such model currently exists. In the first part of this work, a preliminary model, based on ab initio calculations and Gibbs ensemble phase equilibrium calculations, was developed for a single perfluoroether, perfluoromethylpropylether; this work has been accepted for publication. Then, using the above methods plus an extension of the Gibbs-Duhem integration method, a realistic united atom potential model has been developed and then optimized using all available vapor-liquid phase equilibrium data for perfluoroethers. This model is composed of a harmonic function for the bond bending potential, a 7th order polynomial function of cosine (l) for the torsional potential, partial charge, and Columbic interaction for the long-range interaction, and Lennard-Jones potential for van der Waals interaction. This model has been shown to reproduce the phase envelope and the critical properties of the perfluoroethers reasonably well.