Ferroelectric polymers with large electrostriction; based on semicrystalline VDF/TrFE/CTFE terpolymers

This paper discusses a new ferroelectric polymer with large electrostrictive response (～4%) at ambient temperature, which is based on a processable semicrystalline terpolymer comprising vinylidene difluoride (VDF), trifluoroethylene (TrFE), and chlorotrifluoroethylene (CTFE). This VDF/TrFE/CTFE terpolymer was prepared by a combination of bulk polymerization process and a borane/oxygen initiator at ambient temperature. The incorporated bulky CTFE units in the terpolymer seem to reduce the crystalline domain size and move the ferroelectric-paraelectric (F-P) phase transition to near ambient temperature with a very small energy barrier. Some terpolymers exhibited common ferroelectric relaxor behaviors with a broad dielectric peak that shifted toward higher temperatures as the frequency increased, and a slim polarization hysteresis loop at near the dielectric peak (around ambient temperature) that gradually evolved into a normal ferroelectric polarization hysteresis loop with reduced temperature.