Interface-Dominated Time-Dependent Behavior of Poled Poly(Vinylidene Fluoride–Trifluoroethylene)/Barium Titanate Composites

Abstract

Composites in which particles of ferroelectric ceramic phase are randomly dispersed in a polymeric matrix are of interest because of flexibility, conformability, and ease of processing. However, their piezoelectric properties are rather low, unless very high volume fractions of ceramics are used. This brings agglomeration and porosity issues due to the large mismatch between the surface energies of the ceramics and of the polymer. Particle surface modification is a common approach for better dispersion; however, it may bring other effects on the properties of the composites, which are usually concealed by the huge improvement in performance due to the more homogenous microstructure. In this work, we compared poly(vinylidene fluoride–trifluoroethylene)/barium titanate composites containing 15 vol.% and 60 vol.% of pristine ceramic particles or particles modified with an aminosilane or a fluorosilane. Similar morphology, with good particle dispersion and low porosity, was achieved for all composites, owing to an efficient dispersion method. The materials were poled with two different poling procedures, and the piezoelectric coefficient d33, the relative permittivity, and the poling degree of barium titanate were followed in time. We highlighted that, although similar d33 were obtained with all types of particles, the nature of the particles surface and the poling procedure were associated with different charge trapping and influenced the evolution of d33 with time.

Dielectric Characterization of Core-Shell Structured Poly(vinylidene fluoride)-grafted-BaTiO3 Nanocomposites

“…The dielectric constant of PVDF lies in the range of 6 to 12 [ 9 ]. By introducing high dielectric constant nanofillers into the PVDF matrix, such a value can be improved [ 10 , 11 , 12 , 13 , 14 , 15 , 16 ]. Barium titanate (BaTiO 3 , abbreviated as BT) is one of the most explored perovskite ferroelectric materials, thanks to its attractive dielectric and piezoelectric properties, leading to its wide employment in several applications such as in electronic industry [ 17 , 18 , 19 , 20 , 21 , 22 ].…”

“…An optimum concentration of 1.0 wt% was found to give the highest permittivity values, which increased the composite permittivity from 45 to 52 (+16%) at 1 kHz for 700 nm diameter particles. Dalle Vacche et al [ 14 ] obtained an increase of permittivity by 98% (at 0.5 kHz) by adding 15 vol% of 200 nm BT nanoparticles to PVDF-TrFE; however, such an increase was reduced by surface modification of BT by silanes. Carbone et al [ 15 ] obtained even higher permittivity enhancements (42 at 1 kHz vs. the nominal permittivity of 12 for PVDF-TrFE) with 30 vol% loading of 1 μm BT nanoparticles, that could be further enhanced by surface modification.…”

SEBS-Grafted Itaconic Acid as Compatibilizer for Elastomer Nanocomposites Based on BaTiO3 Particles

“…Finally, X-ray diffraction analysis shows that SEBS/BaTiO3 and SEBS/SEBSg-IA/BaTiO3 present characteristic peaks at 22.2°, 31.6°, 38.9° and 45.3°, corresponding to (100), ( 110), ( 111) and (200) planes of cubic BaTiO3 (Figure 7) [34]. The similitude observed in the diffraction patterns of both composites indicates that the mixing of BaTiO3 with polymer does not affect the crystallinity of nanoparticles [35]. Figure 8 shows the dielectric permittivity (8a) and dielectric loss (8b) as function of frequency in the range between 10 −1 and 10 6 Hz, measured at room temperature.…”

Interface coupling and energy storage of inorganic–organic nanocomposites

“…The incompatibility of inorganic and organic contact interfaces and the severe agglomeration of inorganic nanofillers directly affect the energy storage performance of IONCs. 28,29 Therefore, studying the interface coupling mechanism of IONCs is a key scientific issue for improving their energy storage performance.…”

“…2). 29 Therefore, compatibility and dispersion are two important aspects for studying the interface coupling in IONCs. 29 The mechanism of these influencing factors is being explored, and finding of an efficient coupling method is an important research topic.…”