CONFORMATIONAL PROPERTIES OF POLY(VINYLIDENE BROMIDE) AND POLY(VINYLIDENE FLUORIDE)

The conformational properties of trimer molecules modeling poly(vinylidene bromide) (PVDB) and poly(vinylidene fluoride) (PVDF) have been analyzed by the molecular mechanics method of Boyd et al., which takes into account both steric and electrostatic energy. The geometric and energy results show that the increase in steric hindrance on substituting Br for F outweighs the corresponding decrease in electrostatic effects. The geometric parameters calculated for PVDF agree with those estimated by Loufakis et al. from the length of the chain folds and those determined by Hasegawa et al. by X-ray diffraction. Total conformational energies were used to calculate a set of intramolecular interaction energies that by means of the rotational isomeric states model allowed estimation of the characteristic ratios Cr and dipole moment ratios Cm of PVDB and PVDF under unperturbed conditions. The results agree satisfactorily with available experimental values. © 1990, American Chemical Society. All rights reserved.