Relaxor Terpolymers

Relaxor ferroelectrics have been an important scientific research topic subject for over twenty years. The main focus of this investigation has been targeted on semicrystalline VDF/TrFE copolymers.

Ferroelectric polymers that generate mechanical actuation are currently in high demand due to their many desirable properties, such as flexibility, lightweight and high mechanical strength.

A new class of ferroelectric polymer P(VDF-TrFE-CFE) was developed by purposefully introducing defects into the P(VDF-TrFE) copolymers. By introducing these defects into the P(VDF-TrFE) copolymers, the polymer can then be converted from a ferroelectric to a relaxor ferroelectric. Adding the proper defect modifications, 1-chlorofluoroethylene (CFE) in the form of chemical monomer, eliminate effects associated with a normal first order ferroelectric-paraelectric transition.

The structural properties of a class of relaxor ferroelectric polymer, poly(vinylidene fluoride-trifluoroethylene-chlorofluoroethylene) [P(VDF-TrFE-CFE)] terpolymer were investigated and compared with those of the poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymer.

In a collaborative group effort with Dr. François Bauer, President of Piezotech, Hésingue, France (formerly of the Institut Franco-Allemand de Recherches de Saint-Louis) and Professor Qiming Zhang of the Electrical Engineering Department and Materials Research Institute at Pennsylvania State University, they have demonstrated the relaxor ferroelectric behavior of the terpolymer of vinilydene fluoride, trifluoroethylene, and chlorofluoroethylene. [PDF Link to technical paper by Drs. Bauer, Fousson and Zhang]

This new class of semicrystalline terpolymer, P(VDF-TrFE-CFE), is synthesized via a suspension polymerization process and offers many unique properties in comparison with other ferroelectric polymers.

When stressed with an electrical field (~150MV/m), the P(VDF-TrFE-CFE) terpolymer exhibits high electrostrictive strain (>7%) with a relative high modulus (>0.3GPa).

The high room temperature relative dielectric constant (greater than 50) the high-induced polarization and a large energy density, makes the Terpolymer ideal as a highly effective capacitor of energy storage.

The relaxor ferroelectric polymer displays practically no piezoelectric activity, yet it reveals larger electrical field induced piezoelectric coefficients under a large electric DC field.

When stressed with an electrical field of 100V/¼m, the relaxor ferroelectric polymer displays large electrostrictive strain. As a result, the terpolymer reveals larger electrical field induced piezoelectric coefficients under a large electric DC field.

Flash Movie

Science Magazine Article

For more information, please contact:

Dr. François Bauer, President
Piezotech S.A.
9 rue de Colmar
68220 Hésingue
France
Phone: +33-(0)3-89-67-00-46
Fax: +33-(0)3-89-67-50-43
Email: francois.bauer@piezotech.fr