Since the discovery of piezoelectricity in polyvinylidene fluoride (PVDF) by Kawai in 1969, polymers based on vinylidene fluoride (VDF) have attracted research interest due to their application in the fields of sensors, actuators, medical imaging, IR detectors, underwater acoustic transducers and emerging organic electronics. The piezoelectric, pyroelectric, and ferroelectric properties of VDF-based resins as well as their transition behavior were extensively studied during the 70s and 80s. However, the usage of the PVDF homopolymer was limited because it does not crystallize directly into its ferroelectric β-phase. In order to obtain a ferroelectric material, PVDF thick films have to be mechanically stretched and then poled under a high electric field. This fabrication process restricted the development of PVDF-based electroactive devices especially for wearable technologies. On the other hand, PVDF copolymers, such as poly(vinylidene fluoride/trifluoroethylene) P(VDF-TrFE) directly form a ferroelectric crystalline structure from solution or melt. Thin copolymer ferroelectric films can then be easily processed as inks via printing techniques and poled using a moderate voltage.
Recently, a new class of polymers has been developed and commercialized: the relaxor ferroelectric polymers. These printable terpolymers are based on P(VDF-TrFE) with a third monomer, either chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE), which alters the crystalline structure to result in a relaxor ferroelectric. Compared to the normal ferroelectric polymers, such as P(VDF-TrFE), these materials exhibit a narrow electrical hysteresis curve, good mechanical properties, a high dielectric constant at ambient temperature and large deformations under an applied electric field.
This presentation will be an overview of fluorinated electroactive polymers especially in the fast-developing fields of printed and flexible electronics. An emphasis will be given on the efforts by Piezotech, the Arkema subsidiary that is commercializing electroactive fluoropolymers, on its recent work with electroactive polymers for haptic applications as well as a novel approach to computer chip cooling using a polymeric electrocaloric effect.
Larry Judovits, PhD, is a Principal Scientist for Arkema, and has worked for Arkema and its predecessor companies for over 30 years. He is a fellow of both ASTM and the North American Thermal Analysis Society (NATAS). Dr. Judovits has over 25 publications. In addition to his responsibilities for Arkema’s King of Prussia Thermal Analysis lab he also works with Arkema’s Piezotech subsidiary in developing and producing fluoropolymer sensor and actuator materials.
Monday, November 13, 2017
Michael’s at Shoreline
2960 N Shoreline Blvd
Mountain View, CA