Few-layer boron nitride nanosheets exfoliated with assistance of fluoro hyperbranched copolymer for poly(vinylidene fluoride-trifluoroethylene) nanocomposite film capacitor

Boron nitride decorated poly(vinyl alcohol)/poly(acrylic acid) composite nanofibers: A promising material for biomedical applications

In this study, polyvinyl alcohol (PVA) and polyacrylic acid (PAA) nanofibers loaded with boron nitride nanoparticles (mBN) were fabricated by using electrospinning and crosslinked by heat treatment. The physical, chemical, and mechanical properties, hydrophilic behavior, and degradability of composite nanofibers were evaluated. The mechanical properties such as elastic modulus, elongation percentage at the break, and mechanical strength of PVA/PAA nanofibers improved with mBN loading. The thermal conductivity of composite nanofibers reached 0.12 W/m·K at mBN content of 1.0 wt% due to the continuous heat conduction pathways of mBN. In the meantime, while there was no cytotoxicity recorded for both L929 and HUVEC cell lines for all composite nanofibers, the antimicrobial efficiency improved with the incorporation of mBN compared with PVA/PAA and recorded as 68.8% and 75.1% for Escherichia coli and Staphylococcus aureus, respectively. On this basis, the present work proposes a promising biomaterial for biomedical applications such as dual drug delivery, particularly including both hydrophobic and hydrophilic drugs or wound dressing.

Improved polarization and energy density in boron nitride nanosheets/poly(vinylidene fluoride-chlorotrifluoroethylene) nanocomposite with trilayered architecture regulation

A polymer film capacitor with high energy density has attracted great attention in recent decades to fulfil the requirements of miniaturization and light weight for electronics and energy storage systems. The multi-layered nanocomposite exhibits an effective route for developing polymer film with large energy capability due to the advantage of each layer. Here, two sandwich constructions of boron nitride nanosheets (BNNSs)/poly(vinylidene fluoride-chlorotrifluoroethylene) (P(VDF-CTFE)) nanocomposite film were designed to investigate the effects of architecture regulation on energy storage performance, i.e. the nanocomposite serving as an inner layer with pristine films as outer layers, in which the nanocomposite film delivers a strongly polarized behavior and the pristine polymer provides a high breakdown strength. The BNNSs were liquid exfoliated from boron nitride bulk assisted with fluoro hyperbranched copolymer that was adsorbed on the surface of nanosheets via CH-π non-covalent interactions. The presence of fluoro segments improves the compatibility between the nanosheets and the P(VDF-CTFE) matrix. The maximum polarization of 7.9 μC cm^-2 at 300 MV m^-1 is achieved in the tailored sandwich film, and the discharged energy density of 9.1 J cm^-3 is obtained in the current nanocomposite, which benefits from the barrier effect between adjacent layers induced by the redistribution of electric field and emerging charge traps at the interfaces. This sandwich BNNSs/P(VDF-CTFE) nanocomposite provides an insightful prospect for structural design with respect to the advanced application of the polymer film capacitor.

Sandwich-structured poly(vinylidene fluoride-hexafluoropropylene) composite film containing a boron nitride nanosheet interlayer

High performance dielectric polymer materials are a key point for energy storage capacitors, especially film capacitors. In this paper, a sandwich-structured polymer film is constructed to achieve high energy density and high efficiency. High dielectric materials of poly(vinylidene fluoride-hexafluoropropylene) (P(VDF-HFP)) doped with barium titanate (BaTiO₃) are used as the outer layer to achieve a high dielectric constant, and a boron nitride nanosheet (BNNS) layer is inserted between P(VDF-HFP)/BaTiO₃ to obtain a high breakdown field strength of composite films. The results indicate that when the doping amount of the BaTiO₃ nanoparticles reaches 10 wt% and the mass fraction of the BNNS layer is 0.75 wt%, a significant improvement of energy storage performance is obtained. The energy storage density of the P(VDF-HFP)/BaTiO₃/BNNSs composite film can reach 8.37 J cm⁻³, which is higher than 6.65 J cm⁻³ of the pure P(VDF-HFP) film. Compared with the P(VDF-HFP) film doped with BaTiO₃, significant improvement of the breakdown field strength (about 148.5%) is achieved and the energy storage density increases 235% accordingly, resulting from the inserted BNNSs layer blocking the growth of electrical branches and suppressing leakage current. This novel sandwich-structured film shows promising future applications for high performance dielectric capacitors.

A novel composite material formed by adding high dielectric inorganic ceramic particles and BNNSs interlayer into a sandwich-structured film.