Preparation and electroactive phase adjustment of Ag-doped poly(vinylidene fluoride) (PVDF) films

Kim, Seung Hyun; Park, So-Jeong; Cho, Chang-Yeol; Kang, Hyeonbae; Sohn, Eun‐Ho; Park, In Jun; Ha, Jong‐Wook; Lee, Sang Goo

doi:10.1039/c9ra08763j

Cited by 12 publications

(12 citation statements)

References 45 publications

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“…Based on the overall data, we can conclude that by increasing the Ag-BT hybrid filler addition in the composites, the formation of the polar structure β and γ phases of PVDF is promoted, although the major phase remains the α-polymorph. An increase of the electroactive β and γ phases of PVDF as induced by the presence of silver inclusions was also reported in recent literature [ 43 , 44 ]. A detailed nanoscale experimental study combined with DFT calculations demonstrated that the mechanism favoring the formation of polar phases resulted from a polar interfacial coupling between the filler and the molecular chains of the polymer promoting specific polar arrangements, i.e., the presence of electroactive phases [ 44 ].…”

Section: Resultssupporting

confidence: 68%

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Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

et al. 2022

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The role of Ag addition on the structural, dielectric, and mechanical harvesting response of 20%(xAg-(1-x)BaTiO3)-80%PVDF (x = 0, 2, 5, 7 and 27 vol.%) flexible composites is investigated. The inorganic fillers were realized by precipitating fine (~3 nm) silver nanoparticles onto BaTiO3 nanoparticles (~60 nm average size). The hybrid admixtures with a total filling factor of 20 vol.% were embedded into the PVDF matrix. The presence of filler enhances the amount of β-PVDF polar phase and the BaTiO3 filler induces an increase of the permittivity from 11 to 18 (1 kHz) in the flexible composites. The addition of increasing amounts of Ag is further beneficial for permittivity increase; with the maximum amount (x = 27 vol.%), permittivity is three times larger than in pure PVDF (εr~33 at 1 kHz) with a similar level of tangent losses. This result is due to the local field enhancement in the regions close to the filler-PVDF interfaces which are additionally intensified by the presence of silver nanoparticles. The metallic addition is also beneficial for the mechanical harvesting ability of such composites: the amplitude of the maximum piezoelectric-triboelectric combined output collected in open circuit conditions increases from 0.2 V/cm2 (PVDF) to 30 V/cm2 for x = 27 vol.% Ag in a capacitive configuration. The role of ferroelectric and metallic nanoparticles on the increasing mechanical-electric conversion response is also been explained.

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Section: Resultssupporting

confidence: 68%

“…The dielectric, ferroelectric, and piezoelectric properties are enhanced by the conformations with a larger dipole moment, i.e., in the electroactive phases β and γ. The phase composition was observed to be sensitive to the processing strategy and parameters, to co-polymerisation [ 41 , 42 ], or by nanofiller additions [ 43 , 44 ].…”

Section: Resultsmentioning

confidence: 99%

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

et al. 2022

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“…We prepared PVDF particles used as cores in spherical particles of uniform size, as shown in Figure b, through semibatch emulsion polymerization . Previous studies have confirmed that PVDF is induced into the β-phase by cations . Unlike conventional PVDF, where ammonium persulfate is used as an initiator, a large portion of the PVDF particles in the synthesis process have a β-phase (Figure S1).…”

Section: Resultsmentioning

confidence: 99%

“…38 Previous studies have confirmed that PVDF is induced into the β-phase by cations. 39 Unlike conventional PVDF, where ammonium persulfate is used as an initiator, a large portion of the PVDF particles in the synthesis process have a β-phase (Figure S1). To block the conductive pathway near the core PVDF in the β-phase, the silica shell was coated through use of the sol−gel method, as shown in Figure 1a.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

High Discharge Energy Density and Efficiency in Newly Designed PVDF@SiO₂–PVDF Composites for Energy Capacitors

Kim

Kang

Sohn

et al. 2020

ACS Appl. Energy Mater.

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The fabrication of a core–shell structure is an effective method of obtaining a composite film with a high energy density. Herein, we prepared a new type of composite film with high energy density and energy efficiency by using silica-coated core–shells on poly(vinylidene fluoride) (PVDF) particles that comprised a high proportion of polar phases rather than inorganics with high dielectric constants. We prepared PVDF particles with a high proportion of the β-phase using emulsion polymerization. Subsequently, we prepared PVDF@SiO2 core–shell particles by coating silica using the sol–gel method. The resultant PVDF@SiO2–PVDF exhibited a low reduction in the dielectric constant because of the lower amount of silica than that in other dense silica particles, which was verified through dielectric constant measurements and theoretical calculations. In addition, when the PVDF@SiO2 particle contained 40 wt % silica, a high breakdown strength of 598.95 MV/m was confirmed. Therefore, we verified that the PVDF@SiO2–PVDF composite film has a high discharge energy density of 12.051 J/cm3 when the PVDF@SiO2 is 40 wt %. In addition, the domain size is limited by the silica shell, resulting in a high energy efficiency of 88.22%, which indicated a potential for the utilization of the composite film in energy storage devices. These results offer a novel strategy for the development of polymer-based capacitors with high energy densities and efficiencies.

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“…[1][2][3][4] It can be stabilized in its distinct polymorphs, α (TGTG′, form II), β (TTTT, form I), γ (T 3 GT 3 G′, form III), δ and ε depending on the molecular chain conformation during the fabrication process. 3,[5][6][7][8][9][10] Various techniques and treatments such as mechanical (stretching), 11,12 thermal (heat temperature), 13 electrical (poling process) 14 and chemical treatments (effect of solvents or other additives) 9,[15][16][17][18][19] during the processing of PVDF affect the molecular phase stabilization in it and hence, the final properties. Among its all forms, β-PVDF is the most electroactive showing good ferro/piezoelectric properties.…”

Section: Introductionmentioning

confidence: 99%

Dielectric Properties and Phase Stabilization of PVDF Polymer in (1−x)PVDF/xBCZT Composite Films

Garg

Annapureddy

Sekhar

et al. 2021

J. Electron. Mater.

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Polyvinylidene fluoride (PVDF) is a semi-crystalline ferroelectric polymer which can be stabilized in its distinct electroactive polymorphs α and γ by selective processing techniques. In this article, to study the effect of processing temperature and barium calcium zirconium titanate (BCZT) ceramic-doping on PVDF phase stabilization, the pure PVDF and PVDF/BCZT composite films were fabricated by solution-casting and melt-pressing. The Fourier-transform infrared spectroscopy and x-ray diffraction studies showed that the pure PVDF and PVDF/BCZT composite films fabricated by solution-casting possessed the characteristic γ-PVDF peaks while melt-pressing stabilized PVDF mostly in the α-phase. The BCZT ceramic particles were found to have no significant effect on PVDF phase stabilization, but it enhanced the overall crystallinity of polymer matrix. The dielectric studies revealed that the relative permittivity (ε r ) of γ-and α-PVDF phases in pure PVDF film samples was ≈ 10 and 7.5 (at 120 Hz) respectively. The ε r of PVDF/BCZT composite films having 50 wt.% BCZT content synthesized by solution-casting and melt-pressing were estimated to be ≈ 31 and 20 (at 120 Hz), respectively, which was about three times that of pure PVDF film synthesized by the respective technique. The value of loss tangent (tanδ) for pure PVDF films synthesized by solution-cast and melt-press technique were ≈ 0.07 and 0.35 (at 120 Hz) respectively. In temperature-dependent dielectric studies, γ-PVDF showed distinct α-relaxation peak at ≈ 120°C and polymer melting at temperature > 130°C. For α-PVDF, the increase in ε r and tanδ was observed during α-relaxation transition at higher temperatures. The dielectric studies indicated that the introduction of BCZT ceramic particles in PVDF matrix increased the ε r -value by enhancing the dipolar and interfacial polarizations in composites, while the decrease in tanδ-value was observed due to decrease in molecular dipoles with a decrease in wt.% of PVDF content. These phenomena collectively improved the overall electric properties of ceramic/polymer composites which makes them suitable candidates to explore for flexible electroactive material form.

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Preparation and electroactive phase adjustment of Ag-doped poly(vinylidene fluoride) (PVDF) films

Abstract: The ratio of γ- and β-phases of Ag-doped poly(vinylidene fluoride) films was controlled by removing Ag+ using a washing process.

Cited by 12 publications

References 45 publications

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

High Discharge Energy Density and Efficiency in Newly Designed PVDF@SiO₂–PVDF Composites for Energy Capacitors

Dielectric Properties and Phase Stabilization of PVDF Polymer in (1−x)PVDF/xBCZT Composite Films

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Preparation and electroactive phase adjustment of Ag-doped poly(vinylidene fluoride) (PVDF) films

Abstract: The ratio of γ- and β-phases of Ag-doped poly(vinylidene fluoride) films was controlled by removing Ag+ using a washing process.

Cited by 12 publications

References 45 publications

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

Increasing Permittivity and Mechanical Harvesting Response of PVDF-Based Flexible Composites by Using Ag Nanoparticles onto BaTiO3 Nanofillers

High Discharge Energy Density and Efficiency in Newly Designed PVDF@SiO2–PVDF Composites for Energy Capacitors

Dielectric Properties and Phase Stabilization of PVDF Polymer in (1−x)PVDF/xBCZT Composite Films

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High Discharge Energy Density and Efficiency in Newly Designed PVDF@SiO₂–PVDF Composites for Energy Capacitors