Poly PVDF TrFE copolymer

Electrostrictive polymers PVDF based copolymers e.g. Poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) Poly(vinylidene fluoride-hexafluoropropylene) (PVDF-HFP) [81... 

Fig. 29 Evolution of the insoluble fraction versus the absorbed dose and the fluence for a PVDF and a poly(VDF-co-TrFE) copolymer (Reprinted with permission of Elsevier) [47]...

Irradiated PVDF and poly(VDF-co-TrFE) copolymer possess ferroelectric properties that allow the use of such fluorinated polymer in the domain of captors, sensors, and detectors [47,194]. Another interesting property of crosslinked poly(VDF-co-HFP) copolymer is their insolubihty in organic solvent [195]. Cured fluorinated polymers can be processed as membranes for many electrochemical applications such as fuel cell and batteries [196]. For example, a poly(VDF-co-HFP) copolymer has been crossUnked with various systems such as polyols [197], by irradiation with electron beam or y-rays [197] or with aliphatic amines [198] in order to elaborate a solid polymer electrolyte for non aqueous lithium battery [197,198]. This electrolyte is particularly interesting for its ionic conductivity, its adhesion with an electro-conductive substrate and also remarkably enhanced heat resistance. 

Examples of polymers that have a piezoactive response are poled poly(vinylidene fluoride) (PVDF) (151) and its copolymers with trifluo-roethylene co(VDF-TrFE) (152), and the family of odd nylons (153) (see Piezoelectric Polymers). These are partially crystalline materials in which the crystalline regions have a permanent electric dipole moment. These polymers show ferroelectric switching behavior indicating that after poling they have a net... 

State of the Art. Pioneering work in the area of piezoelectric polymers (9) led to the development of strong piezoelectric activity in poly(vinylidene fluoride) (PVDF) and its copolymers with trifluoroethylene (TrFE) and tetrafluoroethylene (TFE). These semicrystalline fluoropolymers represent the state of the art in piezoelectric pol5uners and are currently the only commercial piezoelectric polymers. 

It was found that in several polymers, such as stretched and poled poly(vinylidene fluoride) (PVDF) and its copolymer, poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)), a strong polarization effect is observed under influence on mechanical stress and temperature. This means that piezoelectric and pyroelectric gas sensors can also be designed based on polymers (see Chap. 13 [Vol. 1]). 

In semicrystalline dipole electrets, polar crystallites are present in addition to the polar amorphous phase (Fig. 2b). In die technically most interesting semicrystalline dipole electrets such as polyvinyhdene fluoride (PVDF) and its copolymers with trifluoro ethylene (P(VDF-TrFE)) (Lovinger 1983) or hexafluoropropylene (P(VDF-HFP)), odd Nylons 7 and 11, polyureas, polyureflianes (PU), and some liquid crystalline polymers, the crystallites are ferroelectric (Vasudevan et al. 1979 Hattori et al. 1996). The terpolymer poly(vinyhdene-fluoride-trifluoroethylene— chlorotrifluoroethylene) (P(VDF-TrFE-CTFE)) has been shown to have relaxor ferroelectric properties as the CTFE group destabilizes die long-range order of the ferroelectric phase (Xu et al. 2001). 

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