Towards Flexible Dielectric Materials with High Dielectric Constant and Low Loss: PVDF Nanocomposites with both Homogenously Dispersed CNTs and Ionic Liquids Nanodomains

Abstract

Flexible dielectric materials with high dielectric constant and low loss have attracted significant attention. In this work, we fabricated novel polymer-based nanocomposites with both homogeneously dispersed conductive nanofillers and ion-conductive nanodomains within a polymer matrix. An unsaturated ionic liquid (IL), 1-vinyl-3-ethylimidazolium tetrafluoroborate ([VEIM][BF 4 ]), was first coated on the surface of multi-walled carbon nanotubes (CNTs) by the mechanical grinding. The ILs coated CNTs were then well dispersed in poly(vinylidene fluoride) (PVDF) matrix by melt-blending. The ILs on the surface of CNTs were subsequently grafted onto the PVDF chains by electron beam irradiation (EBI). The formed ILs grafted PVDF (PVDF-g-IL) finally aggregated into ionic nanodomains with the size of 20-30 nm in the melt state. Therefore, novel PVDF nanocomposites with both homogenously dispersed CNTs and ionic nanodomains were achieved. Both carbon nanotubes and ionic nanodomains contributed to the enhancement of the dielectric constant of PVDF significantly. At the same time, such homogeneously dispersed CNTs along with the confined ions in the nandomains decreased current leakage effectively and thus led to the low dielectric loss. The final PVDF nanocomposites exhibited high dielectric constant, low dielectric loss and good flexibility, which may be promising for applications in soft/flexible devices.

Distribution of the Ferroelectric Polarization in Polyvinylidene Fluoride During Initial Poling and Polarization Reversal

“…Assuming   16 [10] and taking into account that о  8.8510 -12 Fm -1 and Е  60 MVm -1 in the case of the middle field, we obtained Рcap  0.79 Ccm -2 .…”

“…6 -Schematic of the processes occurring in PVDF poled in the middle fields, at the moment of short-circuiting (a), the distribution of the field strength at the moment of shortcircuiting (b), and the state of the sample after aging in the short-circuited state charges located either on the electrode or in the near-surface layer injection of charge carriers from electrodes in the formation of polarized zones in PVDF. The concept of the close interrelation between trapped charges and the ferroelectric polarization in PVDF was suggested and proved in several publications [7][8][9][10]. Experimental data indicated that in the case of widely used Al electrodes, the level of injection from the negative metal electrode was higher than from the positive electrode.…”

Enhanced Dielectric Performance of P(VDF-HFP) Composites with Satellite–Core-Structured Fe2O3@BaTiO3 Nanofillers

“…Two main strategies have been developed by researchers to enhance the dielectric permittivity [5,6,7,8,9,10,11,12]. One is incorporating ceramic fillers with intrinsically high dielectric constants (e.g., BaTiO 3 , Ba x Sr 1-x TiO 3 , CaCu 3 Ti 4 O 12 ) [13,14,15,16,17,18,19,20] into the polymer matrix; the other strategy is employing conductive fillers, including metals (e.g., Ag, Ni, Al) [21,22,23,24,25], carbon materials (e.g., carbon nanotubes, graphene) [26,27,28,29,30,31,32], semiconductors (e.g., ZnO) [33], and conductive polymers (e.g., polyaniline (PANI)) [34,35,36,37]. With ceramic/polymer composites, the merits of high ε r from ceramic fillers and high breakdown strength from polymers are combined.…”

Development of Polymer Blends Based on PVA:POZ with Low Dielectric Constant for Microelectronic Applications

“…Dielectric materials have attracted great attention due to their uses in energy storage applications. Among a variety of physical properties, such as high dielectric constant, low dielectric loss and high electric breakdown strength are the mainly significant parameters that offer valuable information concerning the dielectric materials 1 . The demands for polymer materials have progressively increased with the advancement of science and technology.…”