Crystal phase of poly(vinylidene fluoride‐co‐trifluoroethylene) synthesized via hydrogenation of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)

Abstract

Trifluoroethylene addition and thermal treatment induced crystal phase transition in a series of poly(vinylidene fluoride-cotrifluoroethylene) [P(VDF-co-TrFE)] containing varied TrFE molar ratio (6,9,12, and 20 mol %) prepared from the hydrogenation of poly(vinylidene fluoride-co-chlorotrifluoroethylene have been investigated by means of Fourier transform infrared spectral (FTIR), Xray diffraction (XRD), and differential scanning calorimetry (DSC) analyses. The comprehensive applications of the three techniques could distinguish a, b and c phase of P(VDF-co-TrFE) very well. The multipeak fitting technique of DSC is successfully applied to calculate the percentage of different phases in the samples, which allows us to investigate the phase transition process of P(VDF-co-TrFE) precisely. It is found that the crystal phase of P(VDF-co-TrFE) films is turned from a þ c phase (6 mol % TrFE) to a þ c þ b phase (9 and 12 mol % TrFE) to b phase (20 mol % TrFE) at high temperature, and from a þ c phase (6 mol % TrFE) to c þ b phase (9 mol % TrFE) to b phase (>12 mol % TrFE) at low fabricated temperature. Both the fabrication conditions and TrFE addition are responsible for the crystal phase transition of the hydrogenised P(VDF-co-TrFE).

Crystalline polymorphism in poly(vinylidenefluoride) membranes

“…The one larger fluoride atom in TrFE monomer replacing the smaller hydrogen atom in the PVDF monomer induces a strong steric hindrance, which spontaneously induces the all-trans conformation. It was found that the crystal phase of P(VDF-co-TrFE) films is turned from α + γ phase (6 mol% TrFE) to α + γ + β phase (9 and 12 mol% TrFE) to β phase (20 mol% TrFE) at high temperatures, and from α + γ phase (6 mol% TrFE) to γ + β phase (9 mol% TrFE) to β phase (>12 mol% TrFE) at low fabricated temperature [105].…”

Multiscale-structuring of polyvinylidene fluoride for energy harvesting: the impact of molecular-, micro- and macro-structure

“…A lower fabrication temperature favours the formation of polar band g-phases. 99 When an as-cast P(VDF-co-TrFE) (80/20) lm was heated to 200 C for 4 h, then quenched at 100 C, a 43% degree of crystallinity was obtained and the a-phase dominated; when quenched at À20 C, a 56% degree of crystallinity was obtained, and almost 100% b-phase was formed. Therefore, the annealing process affects the local distribution of the TrFE comonomer units in the crystalline lattices, which is reected by the varied T c and crystallinity.…”

“…4. A signicant body of research has demonstrated that nanoparticles with a negatively charged surface can interact with the positively charged -CH 2 groups, and induce the formation of the polar b-phase, with fractions up to 100%, 64,99,128 140 ), and conducting polymers. The effect of nanoparticle additions on the structure and piezoelectric properties of PVDF polymers generally depend on their nucleation efficiency, supercooling effect and interfacial interactions.…”

Crystallization behavior and electroactive properties of PVDF, P(VDF-TrFE) and their blend films

“…The extra TrFE monomers introduced into PVDF chains can change the crystallization behavior of PVDF films [15]. Recent studies reported that P(VDF-TrFE) can directly be crystallized into the polar -phase when the TrFE content is higher than 20 mol%, regardless of the fabrication method and conditions [16]. The Density Function Theory (DFT) simulations revealed that the -phase is easier to obtain in P(VDF-TrFE) because -conformation is more thermodynamically stable than the -conformation, which makes the transition from  to  more difficult 3 [17].…”