Thermal behavior of poly(VDF-ter-TrFE-ter-CTFE) copolymers: Influence of CTFE termonomer on the crystal-crystal transitions

Abstract

Structural evolutions of VDF-based terpolymers with temperature and CTFE content. • Thermal correlation of SAXS-WAXS, DSC, DMA, dielectric spectroscopy and D−E loops data. • One or two crystal-crystal transitions are observed depending on CTFE content. • A model for continuous transition from orthorhombic RFE to hexagonal PE is proposed. • Enhancement of electroactive properties in the temperature range of the RFE-PE transition.

High and Temperature‐Independent Dielectric Constant Dielectrics from PVDF‐Based Terpolymer and Copolymer Blends

“…The relaxor ferroelectric crystalline phase (RFE) was identified in Terpo‐8, with an interplanar distance of 4.91, ( Figure a), while the defective ferroelectric (DFE) and the ferroelectric (FE) phases were found in Copo‐46/54 with distances 4.78 and 4.65 Å, respectively (Figure 4b). These phases are identified in agreement with previous works 21,24. In all the blends, we observe the coexistence of these crystalline phases RFE, DFE, and FE with various amount depending of the composition of the blend (Figure 4c).…”

“…The other maximum correspond to distances between 20 and 37 nm. These dimensions fit well the period of crystalline lamellae observed in this kind of copolymers after annealing 21,23. The sharpest peaks are observed in the Blend‐90/10 (19 and 32 nm) and in Blend‐80/20 (22 and 37 nm).…”

“…PVDF‐based terpolymers have been extensively used as high‐k gate dielectrics in OFET due to their good dielectric properties. However, the structural phase transition of P(VDF‐ ter ‐TrFE‐ ter ‐CFE) around room temperature results in temperature‐sensitive dielectric properties and a serious decrease in permittivity at higher temperature 21,22. To improve the temperature stability of P(VDF‐ ter ‐TrFE‐ ter ‐CFE) material, we present an effective approach by blending different compositions of fluorinated polymers to achieve high and constant dielectric constant at temperature ranging from 20 to 80 °C.…”

“…Relative permittivity, ε r ′, depends on the crystallinity and is maximum at the crystal–crystal transitions from the relaxor‐ferroelectric (RFE) to the paraelectric (PE) phases or from the ferroelectric (FE) to the paraelectric (PE) phases 21. It is worth mentioning that the difficulty to modelize the shape of ε r ′ for a blend of two semi‐crystalline polymers 26.…”

Introducing Functionality to Fluorinated Electroactive Polymers

“…The width of this peak is due to both the separation of the two peaks d 200 and d 110 and the extension of the crystal 14 . The black peak around 2 = 40° corresponds to the juxtaposition of several Bragg peaks mostly characteristic of the order along the chains 22 .…”