Polyimide (PI) dielectric nanocomposites containing functional nanofillers based on layered structure (single-layer: BT@Al 2 O 3 @PI, double-layer: PI/B-T@Al 2 O 3 @PI, three-layer: PI/BT@Al 2 O 3 @PI/PI) were designed and prepared by using PI as matrix, barium titanate (BT)@alumina (Al 2 O 3 ) as nanofillers through in-situ polymerization compounding technology. FTIR tests indicated that PI and PI dielectric nanocomposites have been synthesized successfully.The molecular mass of BaTiO 3 @Al 2 O 3 @PAA oligomer was higher than that of pure PAA when BT and Al 2 O 3 nanofillers were incorporated simultaneously, as verified by GPC and intrinsic viscosity tests. XRD analysis showed that the addition of nanofillers destroyed the order of PI molecular structure and reduced the arrangement density of PI molecular chains. Both FESEM and HRTEM observations showed that the nanofillers were homogeneously dispersed in the PI matrix, contributing to the property improvements of PI dielectric nanocomposites. TGA results indicated that adding nanofillers improved the thermal stability and heat resistance of PI dielectric nanocomposites. The dielectric constant of PI/BT@Al 2 O 3 @PI double-layer nanocomposites was between the single-layer nanocomposites and pure PI. Due to the effective medium theory, the dielectric constant of three-layer PI/BT@Al 2 O 3 @PI/PI nanocomposites containing 5 wt% BT@Al 2 O 3 reached 5.43. This work can be expected to provide an effective strategy to fabricate PI dielectric nanocomposite films for energy storage applications. K E Y W O R D Sbarium titanate (BT), dielectric property, layered structure, polyimide (PI), thermal property | INTRODUCTIONRecently, the applications of high dielectric and high energy storage materials have attracted extensive attention. [1,2] Especially, with the rapid development of

In this study, a new and facile route has been developed to prepare graphene oxide (GO)/sodium benzoate (Sb) compounding nucleator (GO-Sb) reinforced polyamide 6 (PA6) nanocomposites. The effects and mechanism of adding GO/Sb compounding nucleator on the morphology and properties of PA6 nanocomposites were systematically investigated. The experimental resultsshowed that there are electrostatic interaction and π-π conjugation between GO and Sb, which make the GO-Sb compounding nucleator homogenously dispersed in matrix and gain good interfacial adhesion. XRD and DSC analysis revealed that incorporation of Sb improved the formation of γ-crystal. In addition, GO-Sb significantly enhanced the crystallization temperature of PA6 nanocomposites due to "the heterogeneous nucleating effects". The tensile results showed that the tensile strength and elastic modulus of the nanocomposites can be obviously improved by incorporation of GO-Sb compounding nucleator at low contents. The tensile strength and impact strength of the PA6-GO-Sb (100/0.05/0.25) nanocomposite were enhanced by 69.9% and 157.1%, respectively compared with pure PA6. Compared with pure PA6, the thermal conductivity of PA6-GO-Sb (100/0.05/0.25) nanocomposite increased by 258.8%. This simple and effective approach is believed to offer possibilities for broadening the graphene applications with the development of PA6-graphene nanocomposites.

This work employed polymer active agent polyvinylpyrrolidone (PVP) treated barium titanate (BT) nanoparticles (PVP@BT) as functional nanofillers to fill polyimide (PI) matrix to fabricate PI nanocomposite films. The microstructure, dielectric properties, and heat resistance of PI, PI/BT, and PI/PVP@BT dielectric nanocomposite films were investigated. Fourier transform infrared spectrometer (FTIR) indicated that PVP has been successfully coated on the surface of BT nanoparticles. Due to the enhanced aggregation of monomers on the PVP@BT nanoparticles, higher molecular weight and viscosity of PI/PVP@BT nanocomposite films were achieved. Compared with PI/BT nanocomposite films, the dispersion of PVP@BT nanoparticles in PI/PVP@BT nanocomposite films was better, as verified by field emission scanning electron microscope and high‐resolution transmission electron microscopy. Filling a small amount of PVP@BT nanoparticles into the PI matrix improved the dielectric properties of the resultant nanocomposite films. The dielectric constant of the nanocomposite films with 10 wt% filler loading was up to 7.1 at 1000 Hz, which was 2.5 times higher than that of pure PI (2.9). PI nanocomposite film dielectric loss was generally lower than 0.015. Thermogravimetric analysis (TGA) tests verified that both pure PI and PI nanocomposite films showed excellent thermal stability. This work can be expected to provide a new strategy for designing and manufacturing PI dielectric nanocomposite films for energy storage applications.

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