Structure and appearance of residual polarization in thin films of polyvinylidene fluoride prepared via the Langmuir-Blodgett method

Abstract

The relationship between electrophysical properties of super thin Langmuir-Blodgett films of polyvinylidene fluoride and their structural parameters via electron-diffraction and IR-spectroscopy methods was studied. According to analysis of the data, α and γ modifications were formed in addition to the β form. The occurrence of the α and γ species, which were responsible for the conformations TGTG− and T3GT3G−, was detected both from the absorbance bands and from the respective reflections in the electron-diffraction patterns. In addition, the electron-diffraction data showed the formation of stratified textures. The polarization-switching curves acquired at 36°C revealed a low degree of spontaneous polarization within a wide energy distribution of domains, which were characterized by an average coercive field of 400 MV/m that reflected the change of polymorphous transformations in an electric field. Moreover, at 49°C, the spontaneous-polarization-switching curves indicated a process with a low coercive field. The observations probably are related to the higher mobility in the crystals of the α phase that might have eased the spontaneous polarization switching.