Effects of Polymorphism and Crystallite Size on Dipole Reorientation in Poly(vinylidene fluoride) and Its Random Copolymers

Guan, Fangxiao; Wang, Jing; Pan, Jilin; Wang, Qing; Zhu, Lei

doi:10.1021/ma101062j

Cited by 140 publications

(166 citation statements)

References 42 publications

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“…Specially, P(VDF-HFP) exhibits high chemical resistance and high flexibility as a result of the presence of HFP. Additionally, it is more interesting that the introduction of HFP does not change the crystalline structure while mediating the degree [3,4] . In other words, the copolymer P(VDF-HFP) exhibits almost the same crystal structure as PVDF.…”

Section: Introductionmentioning

confidence: 99%

Crystal structure transformation and dielectric properties of polymer composites incorporating zinc oxide nanorods

Dang

et al. 2013

Macromol. Res.

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Abstract.Zinc oxide (ZnO) nanorods were synthesized using a modified wet chemical method. Poly(vinylidene fluoride-co-hexafluoropropylene), P(VDF-HFP), nanocomposites with different ZnO nanorods loadings were prepared via a solution blend route. Field emission scanning electron microscopic (FESEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR) were used to investigate the structure and morphology of the nanocomposites. XRD and FT-IR data indicate that the incorporation of ZnO nanorods promote the crystalline structure transformation of P(VDF-HFP). As the content of ZnO nanorods increases, the β phase structure increases while the α phase decreases. In addition, the dielectric properties of the P(VDF-HFP) and its composites were systematically studied.

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Section: Introductionmentioning

confidence: 99%

Crystal structure transformation and dielectric properties of polymer composites incorporating zinc oxide nanorods

Dang

et al. 2013

Macromol. Res.

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“…The successful grafting of PS side chains from the Cl sites in P(VDF-CTFE) 93/7 was con fi rmed by 19 F NMR, as shown in Figure 1 a. Peak assignment and corresponding integration are summarized in Table 1A and Table 1B , respectively.…”

Section: Synthesis and Molecular Characterization Of P(vdf-ctfe)-g -Pmentioning

confidence: 81%

“…Peak assignment and corresponding integration are summarized in Table 1A and Table 1B , respectively. Comparing the 19 F NMR spectra for P(VDF-CTFE) 93/7 and its PS-graft copolymers, the CTFE-related 19 F signals (peaks c, f, and k in Figure 1 a and Table 1A) disappeared in chemical Figure 1 . A) 19 F and B) 1 H NMR spectra of P(VDF-CTFE) 93/7 and P(VDF-CTFE)-g -PS graft copolymers with 17, 29, 34 and 45 wt-% PS.…”

Section: Synthesis and Molecular Characterization Of P(vdf-ctfe)-g -Pmentioning

confidence: 99%

Confined Ferroelectric Properties in Poly(Vinylidene Fluoride‐co‐Chlorotrifluoroethylene)‐graft‐Polystyrene Graft Copolymers for Electric Energy Storage Applications

Guan¹,

Yang²,

Wang³

et al. 2011

Adv Funct Materials

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143

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Dielectric polymer film capacitors having high energy density, low loss and fast discharge speed are highly desirable for compact and reliable electrical power systems. In this work, we study the confined ferroelectric properties in a series of poly(vinylidene fluoride‐co‐chlorotrifluoroethylene)‐graft‐polystyrene [P(VDF‐CTFE)‐g‐PS] graft copolymers, and their potential application as high energy density and low loss capacitor films. Thin films (ca. 20 μm) are prepared by different processing methods, namely, hot‐pressing or solution‐casting followed by mechanical stretching at elevated temperatures. After crystallization‐induced microphase separation, PS side chains are segregated to the periphery of PVDF crystals, forming a confining interfacial layer. Due to the low polarizability of this confining PS‐rich layer at the amorphous–crystalline interface, the compensation polarization is substantially decreased resulting in a novel confined ferroelectric behavior in these graft copolymers. Both dielectric and ferroelectric losses are significantly reduced at the expense of a moderate decrease in discharged energy density. Our study indicates that the best performance is achieved for a P(VDF‐CTFE)‐g‐PS graft copolymer with 34 wt‐% PS; a relatively high discharged energy density of approximately 10 J cm−3 at 600 MV m−1, a low dielectric loss (tanδ = 0.006 at 1 kHz), and a low hysteresis loop loss (17.6%) at 550 MV m−1.

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“…It was found that both unstretched and stretched PVDF-CTFE were mostly in the nonpolar phase at zero electric field, Under electric field a transition to the polar phase was observed as evidenced by enhanced electric displacement under electric field. Furthermore, evidence for the presence of all three phases was presented by Guan et al [16] based on wide-angle x-ray diffraction and Fourier transform infrared spectroscopy experiments. Although the structural transformation pathway proposed by us has not yet been observed, the low transition barriers calculated above make it a strong candidate for explaining the fast chargedischarge cycles observed experimentally [2].…”

mentioning

confidence: 94%

Electric Field Induced Phase Transitions in Polymers: A Novel Mechanism for High Speed Energy Storage

2012

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Using first-principles simulations, we identify the microscopic origin of the nonlinear dielectric response and high energy density of polyvinylidene-fluoride-based polymers as a cooperative transition path that connects nonpolar and polar phases of the system. This path explores a complex torsional and rotational manifold and is thermodynamically and kinetically accessible at relatively low temperatures. Furthermore, the introduction of suitable copolymers significantly alters the energy barriers between phases providing tunability of both the energy density and the critical fields. DOI: 10.1103/PhysRevLett.108.087802 PACS numbers: 61.41.+e, 71.15.Nc, 77.22.Àd The usual means of storing electrical energy are either batteries, where the current induces chemical reactions, or capacitors, where especially chosen dielectrics enhance the stored energy. Current batteries offer energy densities of about 10 2 -10 3 Wh=kg, but their power densities, i.e., the speeds at which they can be discharged, are only 50-300 W=kg [1]. Fuel cells have energy densities [1] several times larger than batteries, but their power densities are significantly lower. Conventional capacitors have energy densities of only $0:05 Wh=kg, but their power densities reach 10 5 W=kg and they can be fully discharged over 10 6 times, compared to 200-1000 times for batteries. They can thus be used to release or store quick bursts of energy, e.g., in acceleration or regenerative breaking. Ultracapacitors, or electric double-layer capacitors, occupy a middle ground in energy storage. They achieve energy densities of $10 Wh=kg and power densities of $10 3 W=kg [1] by using porous plates suspended in an electrolyte to attract negative or positive ions to the positive or negative electrodes, thereby dramatically shrinking the distance between the positive and negative "layers." This increases the capacitance per unit area, c ¼ " 0 K=d, where K is the dielectric permittivity and d is the distance between capacitor plates. However, the charge-discharge speeds of ultracapacitors are limited by ion diffusion in the electrolyte, while the porosity of the plates leads to small breakdown voltages within each cell. In contrast, by using ultrafast phase transitions as the primary mechanism of energy storage, polyvinylidene-fluoride (PVDF)-based capacitors reach the power densities and breakdown fields of conventional capacitors, while their energy densities are 10 2 -10 3 larger, potentially rivalling those of ultracapacitors.In traditional capacitors, the stored energy density is given by U ¼ 1=2" 0 KE 2 b , where E b is the electric breakdown field. Enhancement of K and/or E b leads to increased energy storage. However, both are native properties that are constants for any chosen material. High K materials such as ferroelectric oxides have low E b . Polymers typically have high E b but very small K. Materials that have both high K and high E b have not yet been found and attempts to create composites with the same characteristics have not yet met with success....

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Effects of Polymorphism and Crystallite Size on Dipole Reorientation in Poly(vinylidene fluoride) and Its Random Copolymers

Cited by 140 publications

References 42 publications

Crystal structure transformation and dielectric properties of polymer composites incorporating zinc oxide nanorods

Crystal structure transformation and dielectric properties of polymer composites incorporating zinc oxide nanorods

Confined Ferroelectric Properties in Poly(Vinylidene Fluoride‐co‐Chlorotrifluoroethylene)‐graft‐Polystyrene Graft Copolymers for Electric Energy Storage Applications

Electric Field Induced Phase Transitions in Polymers: A Novel Mechanism for High Speed Energy Storage

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