Electromechanical properties of poly(vinylidene-fluoride-chlorotrifluoroethylene) copolymer

The electromechanical response of poly(vinylidene-fluoride-chlorotrifluoroethylene) [P(VDF-CTFE)] copolymers with 9 mol % (CT9) and 12 mol % CTFE (CT12) is reported. The CT12 (at room temperature) exhibits an electrostrictive strain response of more than 5% and a piezoelectric constant d(33) of 140 pC/N at a dc bias of 70 MV/m. It is found that about 70% of crystalline regions in P(VDF-CTFE) is at the nonpolar phase and that the CT9 has a crystallinity about 25% higher than the CT12. The difference in electromechanical performance between the CT9 and CT12 cannot be completely explained using the structure/conformation change alone. It is believed that the contribution of the interfacial layers to the polarization and electrostrictive strain response plays an important role.