Quantum Chemistry Based Force Field for Simulations of Poly(vinylidene fluoride)

Abstract

A classical potential function for simulations of poly(vinylidene fluoride) (PVDF) based upon quantum chemistry calculations on PVDF oligomers has been developed. Quantum chemistry analysis of the geometries and conformational energies of 1,1,1,3,3-pentafluorobutane (PFB), 1,1,1,3,3,5,5,5-octofluoropentane (OFP), 2,2,4,4-tetrafluoropentane (TFP), and 2,2,4,4,6,6-hexafluoroheptane (HFH) was undertaken. In addition, an ab initio investigation of the energies of CF4−CF4 and CH4−CF4 dimers was performed. The classical potential function accurately reproduces the molecular geometries and conformational energies of the PVDF oligomers as well as intermolecular interactions between CH4 and CF4. To validate the force field, molecular dynamics simulations of a PVDF melts have been carried out at several temperatures. Simulation results are in good agreement with extant experimental data for PVT properties for amorphous PVDF as well as for PVDF chain dimensions.