Formation Mechanism of β-Phase in PVDF/CNT Composite Prepared by the Sonication Method

Abstract

Two poly(vinylidene fluoride)(PVDF)/carbon nanotube (CNT) composites are prepared by solution sonication and mechanical mixture approaches. It is found that α-phase coexists with β-phase in the composite prepared by sonicating the PVDF/CNT mixture solution, while no β-phase can be observed in the composite prepared from the mechanical mixture route. With the help of the density functional theory calculations, it is explained that a large amount of energy is required for transforming trans−gauche−trans−gauche′ (TGTG′) into trans−trans (TT) conformations and the TT molecular chain can be bound on the CNT surface tightly. The emergence of β-phases is independent of zigzag carbon atoms on the CNT surface. The formation mechanism of β-phase is proposed based on the theoretical calculations and experimental results.

Influence of MWCNTs on β-Phase PVDF and Triboelectric Properties

“…As demonstrated in the XRD results, it was found that the PVDF-PCNTs nanocomposite films consisted of the -phase and the -phase PVDF. The absorbance bands at 613 cm −1 (CF 2 bending), 763 cm −1 (CF 2 wagging vibration), and 975 cm −1 (CF 2 rocking vibration) were related to the -phase [8]. However, the absorbance bands at 838 cm…”

“…In order to demonstrate the transition of PVDF crystalline structures, the pure PVDF and PVDF-MWCNTs composite films are also analyzed; it can be found that three distinctive peaks are observed at three different diffraction angles (2 ): 18.4 ∘ , 19.9 ∘ , and 26.5 ∘ corresponding to (020), (110), and (021) crystal plane from the -phase crystalline structure [8]. When it comes to the PVDF-PCNTs composite films, the peak at 2 = 20.8…”

“…Among all of the available piezoelectric materials, polyvinylidene (PVDF) and its derivatives have been singled out in flexible nanogenerators due to their high dielectric, piezoelectric, and ferroelectric properties [4][5][6]. The -phase of PVDF with the all-trans conformation of fluorine atoms leads to high values of electric polarization to the unit cell [7,8]. Generally, the -phase of the crystalline structure of PVDF can be enhanced by either mechanical deformation in the uniaxial or biaxial directions or application of a highly intense electric field to the PVDF film above its glass transition temperature [9][10][11].…”

Electrically conducting polymer nanostructures confined in anodized aluminum oxide templates (AAO)

“…Nevertheless, studies do not agree on the percolation threshold [40][41][42][43][44] since there is no unique value, as it depends on the process conditions, the possible preferred orientation of the CNTs in the matrix, the CNTs type and their characteristics (i.e. AR, surface modification [45][46][47][48]). In the case of a 5 wt% of MWCNT, the conductivity still increases although flexibility and processability of the polymer is lost as reported by Lonjon et al [49] in the case of P(VDF-TrFE) and nickel nanowires.…”

A facile method to enhance ferroelectric properties in PVDF nanocomposites

“…Various methods have been proposed and implemented [11][12][13][14] to increase the β phase content of PVDF films; however high temperature mechanical stretching and high voltage poling using are proved to be efficient and practical [15][16][17] .…”