Ferroelectricity and molecular dynamics of poly(vinylidenefluoride-trifluoroethylene) nanoparticles

Here we show that ferroelectric polymeric nanoparticles of a poly(vinylidene fluoride-trifluoroethylene) random copolymer, can be prepared by dialysis nanoprecipitation. By this method semicrystalline particles with mean diameter of 280 nm, as revealed by atomic force microscopy, can be obtained. The ferroelectric nature at room temperature of the nanoparticles has been proven by piezoresponse force microscopy, differential scanning calorimetry, X-ray diffraction at wide angles and broad band dielectric spectroscopy. The poly(vinylidene fluoride-trifluoroethylene) nanoparticles exhibit a ferroelectric-toparaelectric transition at lower temperature compared with the bulk. In the paraelectric phase the nanoparticles show an intense dielectric relaxation process associated to the rotational motion of the dipoles within the paraelectric crystalline phase. The nature of this dielectric process is similar to that of the bulk.