Poly(Vinylidene Fluoride) (PVDF) and its Copolymers

Abstract

Abstract Poly(vinylidene fluoride) (PVDF) and its family of copolymers are arguably the best‐known examples of a class of high‐performance polymers noted for their remarkable piezoelectric and ferroelectric properties. After more than 30 years of study and development, the piezoelectricity and electromechanical properties of PVDF and its copolymers have been improved markedly. Today this class of polymer still possesses the highest electromechanical responses over a broad temperature range among known synthetic organic materials. Further, when considered along with their easy conformability, flexibility, robustness, and lightness, it is not surprising that electroactive polymers continue to be the focus of interest of the designers of high‐performance electromechanical devices. When PVDF is stretched and poled in a strong electric field, it exhibits piezoelectricity. In its piezoelectric form, PVDF finds use in transducer devices requiring the interconversion of mechanical and electrical energy. Piezoelectric PVDF can be fabricated and used in a variety of sensors and actuators such as artificial muscles and organs, medical imaging, blood‐flow monitors, microphones, smart skins, underwater acoustic transducers, seismic monitors, fluid pumps and valves, surface acoustic wave devices, robots, and tactile sensing devices. P(VDF‐TrFE) copolymers display similar and in some cases even superior properties. Many organic substances in fact exhibit a key ferroelectric property that is called polarization hysteresis. The copolymer of PVDF with trifluoroethylene (TrFE) and tetrafluoroethylene (TFE), however, is the only polymeric system that shows both a well‐defined polarization hysteresis loop and a transition to a paraelectric phase with increased temperature.