Dielectric spectroscopy of ferroelectric polymers

Kochervinskiĭ, V. V.; Malyshkina, I. A.

doi:10.1016/b978-0-12-821551-7.00001-4

Cited by 3 publications

(7 citation statements)

References 145 publications

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“…The relaxation time of such a mobility in our copolymers is ~0.1–1 μs. This follows from Figure 7 b, where the high-frequency peak of the loss factor is responsible exactly for this type of mobility [ 41 ].…”

Section: Resultsmentioning

confidence: 85%

“…Since the volume charge density and, correspondingly, E sc , is a function of time, as a result, the dielectric permittivity values at low frequencies ( Figure 7 a) are above 100, which is not typical of the materials under study [ 41 ]. Because the TPP-doped film demonstrates a higher conductivity, the relaxation time for formation of the equilibrium space charge (inset to Figure 7 b) is almost two orders of magnitude lower than that for the initial undoped film.…”

Section: Resultsmentioning

confidence: 99%

“…The fraction of the amorphous phase in PVDF is ≈0.5 and may reach ≈0.8 in the copolymers under study [ 35 , 36 ]. At a room temperature, the polymer chains in the amorphous phase undergo micro-Brownian cooperative mobility [ 41 ]. The relaxation time of such a mobility in our copolymers is ~0.1–1 μs.…”

Section: Resultsmentioning

confidence: 99%

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Optical and Electrophysical Properties of Vinylidene Fluoride/Hexafluoropropylene Ferroelectric Copolymer Films: Effect of Doping with Porphyrin Derivatives

Kochervinskiĭ¹,

Gradova

Градов

et al. 2023

Nanomaterials

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Polymer films doped by different porphyrins, obtained by crystallization from the acetone solutions, differ in absorption and fluorescence spectra, which we attribute to the differences in the structuring and composition of the rotational isomers in the polymer chains. According to the infrared spectroscopy data, the crystallization of the films doped with tetraphenylporphyrin (TPP) proceeds in a mixture of α- and γ-phases with TGTG− and T3GT3G− conformations, respectively. Three bonds in the planar zigzag conformation ensures the contact of such segments with the active groups of the porphyrin macrocycle, significantly changing its electronic state. Structuring of the films in the presence of TPP leads to an increase in the low-voltage AC-conductivity and the registration of an intense Maxwell-Wagner polarization. An increased conductivity by an order of magnitude in TPP-doped films was also observed at high-voltage polarization. The introduction of TPP during the film formation promotes the displacement of the chemical attachment defects of “head-to-head” type in the monomeric units into the surface. This process is accompanied by a significant increase in the film surface roughness, which was registered by piezo-force microscopy. The latter method also revealed the appearance of hysteresis phenomena during the local piezoelectric coefficient d33 measurements.

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Optical and Electrophysical Properties of Vinylidene Fluoride/Hexafluoropropylene Ferroelectric Copolymer Films: Effect of Doping with Porphyrin Derivatives

Kochervinskiĭ¹,

Gradova

Градов

et al. 2023

Nanomaterials

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“…Considering polymeric ferroelectrics, which also belong to this class of polymers, the appearance of a fine structure in the amorphous phase is manifested in secondary crystallization [ 7 , 28 ]. Experimental evidence of such processes was obtained using DSC method, where, besides the main (high-temperature) melting process, the low-temperature heat absorption peak was also detected [ 12 ]. It could be assumed that peak halo with the angular position in the ~18° region ( Figure 3 ) indicates formation of a fine structure in the amorphous phase of our copolymer.…”

Section: Resultsmentioning

confidence: 99%

“…VDF-based ferroelectric polymers have high piezoresponse and pyroresponse values, present chemical and thermal stability and are biocompatible. This is why they are of significant interest as materials for flexible electronics and biomedicines [ 12 ].…”

Section: Introductionmentioning

confidence: 99%

The Domain and Structural Characteristics of Ferroelectric Copolymers Based on Vinylidene Fluoride Copolymer with Tetrafluoroethylene Composition (94/6)

Kochervinskii,

Buryanskaya,

Osipkov

et al. 2024

Polymers

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This paper presents data on the macroscopic polarization of copolymer films of vinylidene fluoride with tetrafluoroethylene obtained with a modified apparatus assembled according to the Sawyer–Tower Circuit. The kinetics of the polarization process were analyzed taking into consideration the contributions of both bound and quasi-free (impurity) charges. It was shown that an “abnormal” decrease in conductivity was observed in fields near the coercive fields. This could be associated with the appearance of deep traps of the impurity charge carriers formed by the polar planes of β-phase crystals. The conductivity data obtained from the charge and current responses differed. It was concluded that chain segments contributing to polarization with sufficiently low fields were present in the amorphous phase. A comparison showed that the average size of β-phase crystals (crystals of X-ray diffraction reflection width) was almost one order of magnitude lower than the domain size obtained using piezoresponse force microscopy (PFM). The analysis of the fast-stage dielectric response before and after polarization indicated that as the external polarizing field increased in the ferroelectric polymer chains, conformational transitions occurred according to the T3GT3G− → (-TT-)n и TGTG → (-TT-)n types. This was accompanied by an increase in the effective dipole moment in the amorphous phase chains. The analysis of the IR spectroscopy data obtained in transmission and ATR modes revealed a difference in the conformational states of the chains in the core and surface parts of the film.

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Fluorine-containing ferroelectric polymers: applications in engineering and biomedicine

Kochervinskii,

Gradov,

Gradova

2022

Usp. khim.

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Сегнетоэлектрические сильнополярные фторсодержащие полимеры на основе винилиденфторида относятся к классу электроактивных полимеров, которые используют в различных технических приложениях. В обычных условиях кристаллизации материал получается с текстурой поликристалла, которая после высоковольтной поляризации трансформируется в нецентросимметричную структуру, что сопровождается появлением высокого пьезо- и пироотклика. Такие материалы можно использовать в качестве пироэлектрических конвертеров. Высокие значения ударной вязкости позволяют рекомендовать их в качестве материалов для создания устройств, преобразующих энергию динамических воздействий в электричество, а нелинейность электрического отклика (за счет сегнетоэлектричества) и высокие пробойные поля открывают возможность для реализации емкостных накопителей энергии. Интенсивная динамика в аморфной фазе при нормальных условиях обеспечивает быстрый сброс накопленной энергии во внешнюю цепь. Учитывая значительную долю аморфной фазы (&ap;50%) во фторсодержащих сегнетоэлектрических полимерах и ее высокую диэлектрическую проницаемость, можно изменять энтропию системы, прикладывая электрическое поле. В случае импульсного поля это обеспечивает понижение температуры, поэтому рассматриваемые материалы (особенно в форме композитов) перспективны для создания твердотельных рефрижераторных устройств. Высокая термопластичность полимеров позволяет создавать сенсоры (например, микрофоны) с профилированной поверхностью активной мембраны, обладающие улучшенными характеристиками. Биосовместимостью и низким акустическим импедансом (близким к импедансу биологической ткани) таких полимеров обусловлена возможность их применения в качестве биосенсоров. При наличии в сегнето-электрической пленке доменов создаются сильные локальные электрические поля, которые могут влиять на активность живых клеток. С использованием прямого и обратного пьезоэффектов можно стимулировать жизнедеятельность и управлять функциями различных тканей организма, включая нервную. <br> Библиография — 463 ссылки.

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Dielectric spectroscopy of ferroelectric polymers

Cited by 3 publications

References 145 publications

Optical and Electrophysical Properties of Vinylidene Fluoride/Hexafluoropropylene Ferroelectric Copolymer Films: Effect of Doping with Porphyrin Derivatives

Optical and Electrophysical Properties of Vinylidene Fluoride/Hexafluoropropylene Ferroelectric Copolymer Films: Effect of Doping with Porphyrin Derivatives

The Domain and Structural Characteristics of Ferroelectric Copolymers Based on Vinylidene Fluoride Copolymer with Tetrafluoroethylene Composition (94/6)

Fluorine-containing ferroelectric polymers: applications in engineering and biomedicine

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