P(VDF-TrFE)-based electrostrictive Co/Ter-polymers and its device performance

In our earlier work, we have demonstrated that the high-energy electron irradiation modifies (VDF-TrFE) copolymers from a normal ferroelectric to a relaxor ferroelectric with high electromechanical response. Here, we present two approaches we are taking recently. One is to explore the non-irradiation approach to modify the PVDF-based material to achieve high electromechanical response. A ter-monomer (HFP and CTFE are used here) with a relative large size is added to the copolymer to act as modifiers. The electromechanical and dielectric properties in the terpolymers seem to be similar to those in irradiated copolymers. The other approach addresses the fundamental issue of the low dielectric constant in the currently available electroactive polymers. By making use of composite approach and ultra-high dielectric constant in CuPc, a polymeric composite with very high dielectric constant but the elastic modulus similar to polymer has been demonstrated. The preliminary results indicate that the polymer composite has the potential to generate high strain under much lower field. In parallel to the material development, we investigated device performance based on the irradiated copolymers. The performance of irradiated copolymer multilayers with a thickness up to 1 mm was characterized. The design and device performance of a flextensional actuator fabricated from the irradiated copolymer multiplayer are presented. The flextensional actuator, whose resonance frequency is at a frequency of a few kHz to more than 10 kHz, exhibits more than 1 mm displacement and high force output, which are attractive for many applications.