Pressure-induced relaxor-to-ferroelectric crossover in vinylidene fluoride relaxor terpolymer: a possible explanation to the high performance of the terpolymer nanocomposites

In this paper, we will present electromechanical behavior of the poly(vinylidene fluoridetrifluoroethylene- 1,1-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer under hydrostatic pressure. The dielectric data obtained under controlled hydrostatic pressure suggest a reversible pressure-induced crossover from the relaxor state to a ferroelectric state in the terpolymer (PVDF/TrFE/CFE 64.3/27.6/8.1 mol %). It was also observed that the P(VDF-TrFE-CFE) terpolymer quenched in ice water shows ferroelectric-like hysteresis loop. These results have led us to the theoretical analysis of a charged sphere, with which it was estimated that the change of a bipolar state of nanoparticles in a terpolymer matrix to a unipolar state due to a possible ionization of the medium under applied electric field could induce electrostatic pressure high enough to generate relaxor-to-ferroelectric crossover. The hysteresis loop of polymer-modified reduced graphene oxide/poly(vinylidene fluoride-trifluoroethylene-clorotrifluoroethylene) terpolymer nanocomposite was also measured to ensure that the relaxor-to-ferroelectric crossover may take place in the nanocomposite.