Structure–property study of pristine and dehydrofluorinated poly(vinylidene fluoride) using density functional theory

This study theoretically evaluates the geometrical and piezoelectric properties of pristine polyvinylidene fluoride (PVDF) and dehydrofluorinated polyvinylidene fluoride (DHF–PVDF) utilizing density functional theory. The comparative study is performed to evaluate the β-phase enhancement capability of C=C bonds in PVDF backbone. Both the α and β phases of PVDF consisting of two chains with six monomers each were theoretically analyzed at the DFT/B3LYP-D level of theory. The piezoelectric properties of the structures were interpreted by calculating dipole moments, atomic point charges, vibrational intensities, and HOMO–LUMO energies from the optimized geometries. The structural and piezoelectric properties of both pristine and dehydrofluorinated PVDF were compared with each other to evaluate the effect of double bonds on β-phase crystallinity in modified PVDF structures. The results indicated that the inclusion of double bonds might enhance the stability and polarity of crystalline phases in PVDF but the piezoelectric properties get diminished slightly owing to the removal of hydrogen and fluorine atoms. Graphic abstract