Effect of Cationic Substitution of Metal Species in Poly(vinylidene difluoride) (C 2 H 2 F 2 ) by Ab Initio Calculations.

The stronger activity of poly(vinylidene difluoride) (PVDF; C ₂ H ₂ F ₂ ), related with its high dielectric constant and its ferromagnetic behavior, puts it into the kinds of materials with novel mechanical features to develop new devices with numerous advantages. Even though PVDF is a common piezoelectric polymer with promising multifunctionality, there still has been little progress in theoretically understanding its band structure and the addition of itinerant electrons because of its polymorphous and multiple phases. In this work, we present the structural and electronic properties of 25% doped C ₂ H ₂ F(X) (X = Al, Ni, and Cu) compounds, including high-frequency dielectric constant (ϵ _∞ ) calculations. Our results show that doping induces structural changes, inducing molecular twists due to weak interactions between the different chains, besides increasing ϵ _∞ with itinerant electrons and increasing the band gap with a transition insulator-metal with 25% Ni doping.