Nucleation of the electroactive phase of poly(vinylidene fluoride) by ferrite nanoparticles: surface versus size effects

摘要

Multiferroics and magnetoelectric materials show interesting scientific challenges and technnologial applications in sensors, acuators and data storage. In view of the fact that only a small number of materials show this kind of properties, exhaustive research activity is being pursued towards the development of new composite materials. Multiferroic nanocomposites films composed of piezoelectric poly(vinylidene fluoride) (PVDF) and magnetostrictive nano-size CoFe_2O_4, NiFe_2O_4 or NiZnFe_2O_4 ferrites were prepared by a solution method. Those ferrite nanoparticles have the ability to nucleate the electroactive β-phase of the polymer, providing in this way an easy route for the preparation of magnetoelectric particulate composites. The fact that the different nanoparticles promotes different amount of β-phase nucleation for different concentrations of nanoparticles indicates that filler size is not the most important parameter determining phase nucleation but the filler-matrix surface interaction. Further, when the polymer-ferrite surface interaction is modified through surfactation, the electroactive phase is not nucleated.