Ferroelectric copolymers and terpolymers for electrostrictors: synthesis and properties

In 1998, Q. Zhang et al. demonstrated that large doses of high-energy beta radiation could transform certain vinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymers into high-strain electrostrictors. Since that time, many laboratories, as well as ISL, have processed electron irradiation of P(VDF/sub 50/-TrFE/sub 50/) and P(VDF/sub 70/-TrFE/sub 30/) copolymers. Electric field induced strains higher than 4% could be achieved and have confirmed the results published. Irradiation of copolymers at room temperature has shown that the interesting reproducible relaxor properties can be obtained. It is also known that PVDF/TrFE/CFE terpolymer can show such electrostriction and relaxor properties. These terpolymers are unfortunately not available from commercial sources. We have developed the capability to synthesize these terpolymers. Semi crystalline terpolymers comprising vinylidene difluoride (VDF), trifluoroethylene (TrFE), and 1,1-chlorofluoroethylene (CFE), terpolymers were prepared via a suspension polymerization process. For a specific composition, relevant relaxor properties as well as high dielectric permittivity have been observed. The results will be presented and the key features will be emphasized.