Interfacial engineering tailoring the dielectric behavior and energy density of BaTiO₃/P(VDF-TrFE-CTFE) nanocomposites by regulating a liquid-crystalline polymer modifier structure

Abstract

Dielectric polymer-based nanocomposites have attracted significant attention in recent years for energy storage applications because of their potential high permittivity and breakdown strength. The coupling effect of a nanofiller/matrix interface plays a crucial role in the dielectric and electric properties of polymer-based nanocomposites. In this paper, three kinds of side-chain liquid crystalline fluoric-polymers, denoted as P-nF (n = 3, 5 or 7, which is the number of terminal fluoric groups), were grafted on the surface of BaTiO3 nanoparticles by a surface-initiated reversible-addition-fragmentation chain transfer polymerization method. The nanocomposite films were prepared via core-shell BaTiO3 nanoparticles dispersed in a poly(vinylidene fluoride-trifluoroethylene-chlorotrifluoroethylene) P(VDF-TrFE-CTFE) polymer matrix. The frequency dependent dielectric properties and energy storage capability of the polymer nanocomposites were studied. The results showed that the permittivity and energy densities of the polymer nanocomposites depended on the molecular structure of the modifier, especially the number of electron-rich fluoric groups. Firstly, all modified BaTiO3 nanoparticles were homogeneously dispersed in the polymer matrix, resulting in the polymer nanocomposites presenting a higher breakdown strength compared with the unmodified BaTiO3 nanoparticles. Secondly, the changes in the nanocomposites' permittivity exhibited diversity for three modifiers due to many influential factors. Thirdly, compared with neat P(VDF-TrFE-CTFE), the discharge energy densities of the polymer nanocomposites are all significantly improved. The highest discharge energy densities of nanocomposites with 5 vol% P-3F@BT reached 14.5 J cm-3. These findings suggest that the optimal interfacial modifier should be carefully decided by combining various properties of the nanocomposites for energy storage.

Interface design for high energy density polymer nanocomposites

“…A novel liquid-crystalline polymer PTFMPCS was also investigated by introducing fluoro-atoms into the PMPCS to engineer the surfaces of BaTiO 3 nanoparticles. 107, 201,202 As a result, a significantly improved energy density was achieved by accurate interfacial control using this fluoro-polymer in a polymer nanocomposite. Subsequently, a series of fluoro-liquidcrystalline polymers with three to seven fluoro-atoms were prepared, which were used to engineer the surface of BaTiO 3 platelets and nanoparticles and modulate the performance of the composites.…”

Recent progress on core-shell structured BaTiO3@polymer/fluorinated polymers nanocomposites for high energy storage: Synthesis, dielectric properties and applications

“…particles is around 1700. Reproduced with permission of [117]. Copyright 2018 Royal Society of Chemistry.…”

Recent Advances in the Synthesis of Polymer-Grafted Low-K and High-K Nanoparticles for Dielectric and Electronic Applications

“…Some studies have systematically studied the role of pendant groups in the polymeric shell of encapsulated nanoparticles on the dielectric properties of nanocomposite. For example, Zhang and workers [ 170 ] varied the number of fluorine substituents present on the molecular structure of polymer shell of core shell structured rigid-fluoro-polymer@ BaTiO 3 nanoparticles by performing RAFT polymerization with styrenic monomers containing different number of fluorine (M-3F, M-5F and M-7F) ( Figure 15 A), Evaluation of dielectric performance of the nanocomposites of rigid-fluoro-polymer nanoparticles@ BaTiO 3 (P-3F, P-5F and P-7F) and poly (Vinylidene fluoride-trifluororethylene-chlorotrifluoroethylene (PVDF-TrFE-CTFE) indicated a strong dependance of permittivity and energy densities on the molecular structure of fluorinated styrenic monomer. For 5% loading, the nanocomposite formulated with fluorinated styrenic monomer containing 3F exhibited the highest breakdown strength (542 kV mm −1 ) and highest energy density (14.5 J cm −3 ) which could be attributed to compact interfacial interactions of P-3F with PVDF-TrFE-CTFE matrix.…”