Microstructures and dielectric properties of fluorene polyester ternary nanocomposites optimized by zero-dimensional and two-dimensional fillers

Due to the limitations of dielectric, insulating and mechanical properties, pure polymers could not satisfy the requirements of technological development. Using inorganic fillers with excellent performance to modify it is the mainstream method at present. Ternary hybrid polymer composites can use fillers with excellent dielectric properties to improve their dielectric properties, showing potential in improving electrical insulation, dielectric, and other fields. In this work, fluorene polyester (FPE) films of different components are prepared by the solution blending method using zero-dimensional silica (SiO2) nanoparticles and two-dimensional boron nitride nanosheets (BNNS) as fillers. Compared with SiO2/FPE composite films, ternary films exhibit better dielectric properties, short-term breakdown strength and corona-resistant lifetime. By investigating the interface features of BNNS, SiO2 nanoparticles and FPE matrix as well as the microstructure and properties of the films, the synergism mechanism of BNNS and SiO2 nanoparticles on the performance of FPE composite films is explored. The dielectric properties of the composites are investigated, including dielectric constant, breakdown strength, and corona-resistant lifetime. This article focuses on clarifying the key role of BNNS in the electrical properties of ternary films and provides a theoretical basis for expanding the application of 2D materials in the field of high insulation.