Density Functional Theory calculations of the ferroelectric poly(vinylidene fluoride- chlorotrifluoroethylene) copolymer, compared to those of poly(vinylidene fluoride)

The quantum mechanics calculations of the energetics and structures corresponding to the different representatives structural conformations of poly(vinylidene fluoridetrifluoroethylene) and poly(vinylidene fluoridechlorotrifluoroethylene) copolymers show that the all-trans, Tp conformation, is energetically stabilized even with a chlorine substituent. The changes in the molecular arrangement associated to Tp or TGa conformations lead to significant changes in shape and electrical-chemical properties. A larger dipole moment and a orientational charge polarization were obtained for the all-trans Tp molecular structure even with a sort chlorine contamination. According to the computed results, the Curie transition temperature should be smaller in P(VDFCTFE) than in PVDF. The fluorine NMR spectra were calculated for the different representative systems. The B3LYP functional and the 6311+G(d,p) bases set were used with the Gaussian program for carrying out the calculations.