Synchronously improved dielectric and mechanical properties of polar-phase-preferential polyvinylidene fluoride films

Gong, Yutie; Zhou, Weijie; Li, Hairong; Pei, Xianglin; Wu, Wenjing; Zhan, Ziwei; Jiang, Ming; Gong, Wei

doi:10.1007/s10854-022-07983-7

Cited by 5 publications

(7 citation statements)

References 36 publications

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“…The initial slight increase is due to a better matching of feed rate and airflow pressure, but after a further increase in feed rate, the current airflow pressure is insufficient to stretch the PVDF chains completely. In the x‐ray diffraction (XRD) patterns, the three main characteristic 2 θ peaks at 18.6°, 20.1°, and 20.6° are assigned to the α (020), γ (110), and β (110)/(200) crystal planes of PVDF, respectively 27–30 . The characteristic peaks of the α (020) and γ (110) crystal planes are stronger at higher feed rates from the XRD patterns (Figure 2C).…”

Section: Resultsmentioning

confidence: 96%

“…The all-trans conformation (β-phase) of PVDF has excellent dielectric, piezoelectric, and ferroelectric properties, followed by the T 3 GT 3 Ḡ conformation (γ-phase) and the TGTḠ conformation (α-phase) having no polarity (Figure 2A). [27][28][29][30] Among the several crystal phases of PVDF, the β-phase has the highest potential energy and is difficult to obtain by conventional processing methods. However, the β-phase is easily obtained by SBS due to the traction orientation of the airflow on the PVDF chains.…”

Section: Molecular Chain Conformationmentioning

confidence: 99%

“…In the x-ray diffraction (XRD) patterns, the three main characteristic 2θ peaks at 18.6 , 20.1 , and 20.6 are assigned to the α (020), γ (110), and β (110)/(200) crystal planes of PVDF, respectively. [27][28][29][30] The characteristic peaks of the α (020) and γ (110) crystal planes are stronger at higher feed rates from the XRD patterns (Figure 2C).…”

Section: Molecular Chain Conformationmentioning

confidence: 99%

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Simple regulation of dielectric pulsing properties of polyethylene glycol‐poly(vinylidene fluoride) coaxial nanofiber films based on blow‐spinning process

Li,

Gong,

et al. 2023

Polymer Engineering & Sci

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Understanding the relationship between the fabrication process and the dielectric behavior of thermo‐responsive dielectric materials and accordingly optimizing the dielectric response behavior through simple regulation is critical to advancing their practical applications. For this purpose, we systematically analyze and demonstrate the effects of blow‐spinning process parameters, the feed rate and airflow pressure, on the orientation of poly(vinylidene fluoride) (PVDF) chains, the individual phase fractions of PVDF, the structure of the core‐sheath nanofibers, the mechanical properties, and the dielectric pulsing properties in polyethylene glycol (PEG)‐PVDF core‐sheath fiber films, and achieve the goal of effectively regulating the thermo‐responsive dielectric behavior. In particular, by increasing the airflow pressure, the polar phase fraction of the PVDF can be effectively increased, thus strengthening the dielectric pulsing effect. The significant influence of the processing parameters on the nanofiber structure also allows us to tailor the strength and toughness of the nanofiber films over a wide range by adjusting the feed rate and airflow pressure. Our work shows that the regulation of feed rate and airflow pressure can be used as an effective strategy to optimize the dielectric pulsing and mechanical properties of PEG‐PVDF films, enabling a simple and low‐cost performance optimization of thermo‐responsive dielectric materials.Highlights Effective regulation of thermal dielectric behavior by tuning process parameters. Simple tuning of mechanical properties of nanofiber films over a wide range. High ratio of β‐ and γ‐phases of PVDF by solution blow spinning. Major polar phases contribute to improved mechanical and dielectric properties.

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Section: Resultsmentioning

confidence: 96%

Section: Molecular Chain Conformationmentioning

confidence: 99%

Section: Molecular Chain Conformationmentioning

confidence: 99%

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Simple regulation of dielectric pulsing properties of polyethylene glycol‐poly(vinylidene fluoride) coaxial nanofiber films based on blow‐spinning process

Li,

Gong,

et al. 2023

Polymer Engineering & Sci

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“…PVDF is a semi-crystalline polymer, and its crystalline phase usually affects its dielectric properties. The crystalline phase content of PVDF is calculated from the FTIR data, [29,[40][41][42][43] as shown in Figure S4 (Supporting Information). It is found that the fraction of the polar phases (𝛽-and 𝛾-phase) of the PVDF decreases monotonically with increasing core feed rate (Figure 2c).…”

Section: Morphological and Structural Characterizationmentioning

confidence: 99%

“…Moreover, the intensities of the characteristic peaks of PEG increase gradually from PVDF@PEG-1 to PVDF@PEG-6, which corresponds to the larger loading content of PEG with an increasing feed rate of the core. Meanwhile, these characteristic peaks of PVDF are observed in the XRD patterns of all PVDF@PEG specimens, [29,[40][41][42][43] as shown in Figure 2b. The two main characteristic 2𝜃 peaks at 17.7°and 18.4°are assigned to the 𝛼 (100) and 𝛼 (020) reflections of the 𝛼-phase of PVDF, respectively.…”

Section: Morphological and Structural Characterizationmentioning

confidence: 99%

Relaxation‐Induced Significant Room‐Temperature Dielectric Pulsing Effects

Gong

et al. 2023

Adv Funct Materials

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Thermo‐responsive dielectric materials are in urgent demand owing to the rapid development of smart electronic/electrical systems. Although different types and structures of thermally responsive dielectric materials have been continuously reported, their dielectric response behaviors all originate from thermodynamic phase transitions. Herein, it is demonstrated that structural relaxation in poly(vinylidene fluoride) (PVDF), a non‐thermodynamic phase transition, can induce a significant thermal dielectric pulse at room temperature. The dielectric pulse strength of up to 6.3 × 105 at 20 Hz, with a dielectric pulsing temperature of 24 °C, is achieved from polyethylene glycol (PEG)‐PVDF coaxial nanofibrous films (PVDF@PEG), fabricated via a continuous blow spinning method. Moreover, the films exhibit excellent flexibility, adjustable strength and toughness, switchable hydrophilicity/hydrophobicity, and effective thermal management capability. The relaxation‐induced dielectric pulsing effect, outstanding multifunctionality, and simple preparation combine to promote further scalability and prospects of PVDF@PEG. In particular, the work contributes to the discovery of the relaxation‐induced dielectric response mechanism, which provides a new strategy for the generation of thermo‐responsive dielectric materials.

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Hydrogen Bond Reorganization‐Enabled Dielectric Pulsing Effects in Polar Polymers

Li,

Gong,

et al. 2023

Adv Funct Materials

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Phase transition and relaxation, both essentially molecular motions, are critical mechanisms that determine the mechanical, electrical, optical, and thermal behaviors of polymer materials. For decades, hydrogen bonding has played an essential role in the modulation of molecular motions and material properties. However, in the design of stimulus‐responsive dielectric materials and the modulation of their properties, the role of hydrogen bonding has been rarely investigated, and its effect on dielectric response behavior remains elusive. Here, observations and proof that hydrogen bond reorganization is able to act as the origin of the dielectric pulsing effect in polar semicrystalline polymers by in situ testing is presented. A two‐step hydrogen bond reorganization drives molecular chain relaxation in polar semicrystalline polymers causing a strong dielectric response behavior, opening up the possibility of modulating dielectric response behavior through hydrogen bonding. Moreover, electrode polarization can synergize with interfacial and dipolar polarizations to enhance the dielectric pulsing effect. This study also provides a blow‐spinning method for preparing large‐area, flat, flexible, lightweight, and recyclable thermo‐responsive dielectric films by continuous, efficient, and low‐cost processing.

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Synchronously improved dielectric and mechanical properties of polar-phase-preferential polyvinylidene fluoride films

Cited by 5 publications

References 36 publications

Simple regulation of dielectric pulsing properties of polyethylene glycol‐poly(vinylidene fluoride) coaxial nanofiber films based on blow‐spinning process

Simple regulation of dielectric pulsing properties of polyethylene glycol‐poly(vinylidene fluoride) coaxial nanofiber films based on blow‐spinning process

Relaxation‐Induced Significant Room‐Temperature Dielectric Pulsing Effects

Hydrogen Bond Reorganization‐Enabled Dielectric Pulsing Effects in Polar Polymers

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