The influence of intramolecular dipole-dipole interaction changes on structure formation peculiarities and some electrophysical properties were investigated with example of copolymers of vinylidene fluoride with tetrafluoroethylene and hexafluoropropylene with different compositions. The decrease of such dipole-dipole interactions in vinylidene fluoride/tetrafluoroethylene copolymers leads to an increase of the a and b parameters of the ferroelectric phase lattice and were accompanied by a shift of the Curie point to lower temperatures. The presence of peak-halo at angles near 20 = 18 degrees were attributed to a paraelectric phase localized in the interfacial domains at the crystal-amorphous phase boundaries. Similar peak-halos for vinylidene fluoride/hexafluoropropylene copolymers crystallizing into the nonpolar alpha phase were associated with the presence of an antiferroelectric phase formed by the chains in the planar zigzag conformation. The temperature range where dielectric anomalies were detected was characterized by conformational changes at which the decrease in planar zigzag conformation isomers took place. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 116: 695-707, 2010