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

Abstract

Dielectric properties of poly(vinylidene fluoride)-grafted-BaTiO3 (PVDF-g-BT) core-shell structured nanocomposites obtained from Reversible Addition Fragmentation chain Transfer (RAFT) polymerization of VDF were investigated by Broadband Dielectric Spectroscopy (BDS). The dielectric constant increased along with the BT content, about +50% by addition of 15 vol% of BT, which was around 40% more than expected from predictions using the usual dielectric modeling methods for composite materials, to be ascribed to the effect of the interfacial core-shell structure. The known dielectric relaxations for PVDF were observed for the neat polymer as well as for its nanocomposites, not affected by the presence of nanoparticles. A relaxation process at higher temperatures was found, due to interfacial polarization at the amorphous-crystalline interface, due to the high crystallinity of materials produced by RAFT. Isochronal BDS spectra were exploited to detect the primary relaxation of the amorphous fraction. Thermal analysis demonstrated a very broad endotherm at temperatures much lower than the usual melting peaks, possibly due to the ungrafted fraction of the polymer that is more easily removable by repeated washing of the pristine material with acetone.

Fluoropolymer Nanoparticles Synthesized via Reversible-Deactivation Radical Polymerizations and Their Applications

“…The high surface energy and large specific surface area of ceramic nanoparticles cause aggregation in the polymer matrix, giving rise to electron conduction with considerable dielectric loss, poor breakdown strength, and other deteriorated electrical properties. To achieve homogeneous nanoparticle dispersion, surface modification of ceramic nanoparticles based on the grafting from strategy (section ) has been shown as a powerful tool. , …”

“…With PVDF@BaTiO 3 made via SI-RAFT polymerization, Raihane et al reported that the core–shell FPNPs provide enhanced dielectric permittivity of about 50% higher than the prediction of the nanocomposite based on the Maxwell Garnett dielectric model, suggesting the promising PVDF/BaTiO 3 interface achieved by grafting from polymerization.…”

“…To achieve homoge-neous nanoparticle dispersion, surface modification of ceramic nanoparticles based on the grafting from strategy (section 4) has been shown as a powerful tool. 195,289 Based on the low surface energy of fluoropolymers, Ma and co-workers 199 prepared poly(13FOMA)@BaTiO 3 nanocomposites via SI-ATRP reaction (Figure 14). The intrinsic nature of C−F bonds is beneficial to decrease the polarization of materials.…”

“…When employing SI-RAFT polymerization, this technique avoids metal-contamination concerns in the polymer synthesis process, which is favorable for preventing high leakage currents under high electric fields. 289 In 2018, Zhang and co-workers 203 fabricated core−shell structured PTFMPCS@BaTiO 3 via SI-RAFT (Figure 14) and blended these nanohybrids with the poly(VDF-TrFE-CTFE) matrix. This work demonstrates that the shell thickness affects the dielectric constant, breakdown strength, and energy density.…”

Improving Mechanical and Barrier Properties of Antibacterial Poly(Phenylene Sulfide) Nanocomposites Reinforced with Nano Zinc Oxide-Decorated Graphene

“…This may be attributed to the fact that the nanofiller can promote the nucleation of PPS [36,37]. As the concentration of G-ZnO increases, the number of nuclei increases, which increases the crystallization rate but hinders the growth of nuclei, resulting in smaller crystalline sizes [38,39]. As a result, PPS/G-ZnO nanocomposites are more likely to melt at lower temperatures during the heating process.…”