Yue Zhang,Tiandong Zhang,Lizhu Liu,Qingguo Chi,Changhai Zhang,Qingguo Chen,Yang Cui,Xuan Wang,Qingquan Lei
High-performance energy storage materials are of essential importance in advanced electronics and pulsed power systems, and the polymer dielectrics have been considered as a promising energy storage material, because of its higher dielectric strength and more excellent flexibility compared with that of inorganic ceramic dielectrics. However, the energy storage capability of pristine polymer has been limited by its low intrinsic dielectric permittivity and ordinary ferroelectric performance. Herein, this work demonstrates a favorable method to achieve a sandwich-structured poly(vinylidene fluoride) (PVDF)-based composite by the electrospinning, solution casting, thermal quenching, and hot-pressing process. This innovative method combines with the 0.5Ba(Zr0.2Ti0.8)O3-0.5(Ba0.7Ca0.3)TiO3 nanofibers (BZT-BCT NFs), which possesses good ferroelectric hysteresis, and the hybrid particles of hexagonal boron nitride nanosheets (BNNSs) coated by ferroferric oxide (Fe3O4@BNNSs), which hold high breakdown strength (Eb). It is worth mentioning that the Fe3O4 particles disperse well on the surface of BNNSs to form the dipoles with the BNNSs at the interfacial region, resulting in an enhancement of the electric displacement and the dielectric permittivity of the composite. Furthermore, the influence of the volume fraction of filler particles on the electrical performance of composite was systematically investigated. Notably, the enhanced performance in terms of electric displacement (D), Eb, and discharged energy density (Ue) was achieved in the sandwiched BZT-BCT NFs-PVDF/Fe3O4@BNNSs-PVDF/BZT-BCT NFs-PVDF composite. The Ue of ∼8.9 J/cm3 was achieved at 350 kV/mm, which was 740% higher than the Ue of biaxially oriented polypropylene (BOPP, Ue ≈ 1.2 J/cm3 at 640 kV/mm). Of particular note is that the hybrids Fe3O4@BNNSs play a critical role to enhance the D and Eb and suppress the remnant displacement (Dr) of sandwiched composite. This contribution proposes an efficient and scalable method to prepare polymer-based dielectric composite for the demanded applications.
To overcome the challenges of agglomeration and the difficulty in achieving oriented alignment of hexagonal boron nitride nanosheets (BNNSs) in epoxy matrices, a magnetically responsive Fe 3 O 4 /BNNSs composite was successfully prepared. Fe 3 O 4 nanoparticles grown in situ on the BNNS surface impart magnetic responsiveness to the nanosheets, enabling their alignment under an external magnetic field, while the BNNSs themselves serve as the primary impermeable barrier filler. By applying a horizontal magnetic field during the curing stage, the nanofillers are driven to align parallel to the substrate, forming an ordered layered structure. Comprehensive characterization confirmed the in-situ growth of Fe 3 O 4 nanoparticles on the BNNS surface and demonstrated the composite’s strong superparamagnetic behavior. Performance evaluation revealed that the epoxy coating containing magnetically aligned Fe 3 O 4 /BNNS fillers (BFM/EP) exhibited the most superior overall properties. After 20 days of immersion in deionized water, the BFM/EP coating displayed a remarkably low water absorption of only 6.48%, compared with 19.28% for the pure epoxy coating, indicating significantly enhanced anti-permeability. Benefiting from the improved barrier performance, the BFM/EP coating also retained the highest adhesion after 14 days of salt-spray exposure. Long-term electrochemical impedance spectroscopy (EIS) over 40 days further demonstrated that BFM/EP exhibited the highest coating resistance (1.93 × 10 8 Ω·cm 2 ), the lowest coating capacitance (1.99 × 10 -10 F·cm 2 ), and the largest low-frequency impedance modulus (1.69 × 10 10 Ω·cm 2 ). These results indicate that the dominant enhancement in corrosion protection originates from the magnetic-field-induced parallel alignment of high-aspect-ratio BNNSs, while Fe 3 O 4 functionalization mainly enables magnetic manipulation and contributes to improved filler dispersion. The resulting ordered filler network effectively enhances the tortuous diffusion pathway for corrosive species, leading to superior impermeability and long-lasting corrosion protection.
A novel magnetic boron nitride nanosheets (Fe 3 O 4 @BNNSs) composite-based magnetic solid-phase extraction (MSPE) method was employed to analyse six plant growth regulators (PGRs) in tomatoes combined with high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The novel Fe 3 O 4 @BNNSs composite was prepared via an in situ chemical coprecipitation process and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Several factors that may affect the extraction efficiencies were optimized. Under the optimal factors, low limits of detection (0.002–0.010 ng g −1 ), good linear ranges (0.05–10 ng g −1 ) and satisfactory precisions (intra-day: 1.2%-3.9%; inter-day: 2.1%-6.9%) were achieved. The established approach was successfully employed to extract and determine PGRs in tomatoes, and the spiked recoveries were between 85.2 and 109.0%.
危险品化学品经营许可证（带存储）