Relaxor fluorinated polymers: Novel applications and recent developments

A new class of ferroelectric polymers, i.e., the terpolymers of P(VDF-TrFE-CFE) and P(VDF-TrFE-CTFE), was developed from the normal ferroelectric PVDF polymer by employing proper defect modifications which eliminate detrimental effects associated with a normal first order F-P transition while maintaining high material responses. The introduction of the third monomer into the polymer chain serves to interrupt the ferroelectric domains, thereby reducing their size. Addition of defects in the form of chemical monomers, in this case 1, 1-chlorofluoroethylene (CFE) or chlorotrifluoroethylene (CTFE) which are copolymerised with the VDF-TrFE, eventually favor the TG conformation and eliminate the normal ferroelectric phase, leading to a relaxor ferroelectric with electromechanical strain that leads to the observed large electrostrictive strain greater than 7% and an elastic energy density of 0.7 J/cm3 at. This high electrostrictive strain coupled with relatively high modulus (>0.3GPa) makes the polymers suitable as a structure component in addition to the electroactive functions (actuators and sensors).