Electronic properties of poly(vinylidene fluoride): a density functional theory study

Ortiz, Erlinda V.; Cuán, A.; Badillo, Carlos Zubieta; Cortés-Romero, Carlos M.; Wang, Qing; Noreña, L.

doi:10.1080/08927020802680729

Cited by 9 publications

(6 citation statements)

References 25 publications

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“…Figure 2 shows that the TG a , TG p and T p are stable geometric conformations for all the materials, because all of them are situated at minimum positions within the PES. We shall bear in mind that the molecular energy computed in this simplified model is far away from that of the real crystal (formed by large domains); nevertheless, computing simulations are consistent with available experimental observations Ortiz et al, 2009;Ortiz et al, 2010). According to Figure 2, it is possible to observe that for all the materials, the TG phases are energetically more stable than the T p phase, and that the PVDF-PES profile shows a symmetric curve distribution, vide Figure 2(a); which is mostly due to the symmetric disposition of fluorine substituents.…”

Section: Active Phase Formationmentioning

confidence: 92%

Quantum Chemical Investigations of Structural Parameters of PVDF-based Organic Ferroelectric Materials

Elba¹,

Cuán²,

Luis³

et al. 2010

Ferroelectrics

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Section: Active Phase Formationmentioning

confidence: 92%

Quantum Chemical Investigations of Structural Parameters of PVDF-based Organic Ferroelectric Materials

Elba¹,

Cuán²,

Luis³

et al. 2010

Ferroelectrics

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“…For the all-T conformation, the dipole moment in the vacuum computed by the ReaxFF force field is 2.16 D, which agrees very well with the value of 2.10 D reported by Nishiyama et al 45 For the TGTG′ conformation, the dipole moment of repeat unit (−CH 2 −CF 2 −) in the vacuum is 1.33 D in ReaxFF and 1.30− 1.32 in the literature. 45,46 Furthermore, we validate the ReaxFF force field in terms of the polarization of different condensed phases against the experimental measurements found in the literature. 47−49 Similar to the adiabatic pathways generated in the Berry-phase method, we prepared two polarization lattices, as exhibited in Figure 11.…”

Section: Resultsmentioning

confidence: 53%

“…Therefore, the ReaxFF force field is parameterized with the partial atomic charges calculated by Karasawa et al using the Hartree–Fock wave function . In ReaxFF, the partial atomic charges are determined by the electronegativity equalization method (EEM). − After the parameters are optimized for atomic charges, the dipole moments of monomeric repeat unit (−CH 2 –CF 2 −) for the TGTG′ and all-T conformations are calculated with the ReaxFF force field, which are compared with the data reported in the literature. − Furthermore, the ReaxFF reactive force field is validated by comparing the ReaxFF-MD simulated spontaneous polarization μ⃗ for the β phase PVDF crystalline with the reported values. − The polarization is defined with eq where Q is the atomic charge, x ⃗ is the atomic displacement, and V is the crystalline volume. However, the polarization is a multivalued quantity in a system with periodic boundaries (i.e., a polarization lattice with equally spaced branches).…”

Section: Methodsmentioning

confidence: 99%

C/H/O/F/Al ReaxFF Force Field Development and Application to Study the Condensed-Phase Poly(vinylidene fluoride) and Reaction Mechanisms with Aluminum

et al. 2022

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Poly(vinylidene fluoride) (PVDF) is a well-known polymer with a (−CH2–CF2−) n chemical formula that is used, in particular, in electronic devices. The spatial arrangements of −CH2– and −CF2– units and the spatial alignment of PVDF chains determine the ferroelectricity, pyroelectricity, and piezoelectricity of condensed-phase PVDF. PVDF can be fabricated with Al metal as an energetic composite for rocket propellants. To better understand how PVDF molecular structures affect the properties in the condensed phase and the chemical reaction mechanisms with Al, we have developed a C/H/O/Al/F ReaxFF force field through parameterization against data from quantum mechanical (QM) calculations and experiments. This ReaxFF force field demonstrates good transferability in both low-temperature regimes, dominated by nonreactive conformational changes, and high-temperature regimes, dominated by PVDF chemical conversion. In the low-temperature regime, we investigated the α → β crystalline phase transition kinetics induced by a poling electric field or mechanical deformation. The molecular dynamics (MD) simulations show that electric field magnitude thresholds for the α → β crystalline phase transitions are 5.0 and 7.5 GV/m in the y and x directions, respectively. In addition, we found that the trans-gauche+–trans-gauche– conformation in the α crystalline structure transforms to the all-trans conformation through mechanical deformation. However, the all-trans chains are arranged in an antiparallel pattern in the stretched structure, resulting in zero polarity. We also observed that the poling electric field threshold can be reduced by combining it with mechanical deformation. In the high-temperature regime, we analyzed the reactions between PVDF and surface-oxidized Al nanoparticles. Results indicate that the reactions are triggered by the absorption of an H or F atom from PVDF to the alumina surface, followed by HF formation from PVDF pyrolysis. The produced HF molecules rapidly react with the surface alumina to form OH and AlF x . The activation energy of AlF x formation is estimated using Arrhenius analysis. In addition, OH groups combine to produce H2O vapor, whereas AlF x aggregates. Moreover, AlC x is also produced. The developed C/H/O/F/Al ReaxFF force field can serve for future studies of composite materials involving Al, alumina, PVDF, and its copolymers.

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“…For the -phase (space group Pna2 1 and the same experimental lattice constants as the ↵-phase), for which we performed one calculation, our predicted values of a, b, and c are 4.85 Å, 10.16 Å, and 4.91 Å. The mean dipole moment (i.e., averaged over the three orthogonal directions) of a single six-unit ↵-chain predicted from the MSXX force field is 1.39 D, which compares well to the DFT calculation by Ortiz et al of 1.32 D. 54 The spontaneous polarization of the bulk -phase is 0.060 C/m 2 , which compares well to the experimental value of 0.07 C/m 2 of Li et al 55…”

Section: A Msxx Force Fieldmentioning

confidence: 91%

Energy barriers for dipole moment flipping in PVDF-related ferroelectric polymers

McGaughey

2016

The Journal of Chemical Physics

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Energy barriers for flipping the transverse dipole moments in poly(vinylidene fluoride) (PVDF) and related copolymers and terpolymers are predicted using the nudged elastic band method. The dipole moments flip individually along the chain, with an order and energy barrier magnitudes (0.1-1.2 eV) that depend on the chain composition and environment. Trifluoroethylene (TrFE) and chlorofluoroethylene (CFE) monomers have larger energy barriers than VDF monomers, while a chain in an amorphous environment has a similar transition pathway as that of an isolated molecule. In a crystalline environment, TrFE and CFE monomers expand the lattice and lower the energy barriers for flipping VDF monomers. This finding is consistent with experimental observations of a large electrocaloric effect in P(VDF-TrFE-CFE) terpolymers.

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Electronic properties of poly(vinylidene fluoride): a density functional theory study

Cited by 9 publications

References 25 publications

Quantum Chemical Investigations of Structural Parameters of PVDF-based Organic Ferroelectric Materials

Quantum Chemical Investigations of Structural Parameters of PVDF-based Organic Ferroelectric Materials

C/H/O/F/Al ReaxFF Force Field Development and Application to Study the Condensed-Phase Poly(vinylidene fluoride) and Reaction Mechanisms with Aluminum

Energy barriers for dipole moment flipping in PVDF-related ferroelectric polymers

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