Organic dyestuff modifier enhancing energy storage performance of PEI-based nanocomposites

[Display omitted] •Providing a novel surface modifier for rigid structural polymers.•Surface modification improving the quality of nanocomposite films.•The energy density of mBT/PEI is significantly enhanced to 4.2 J cm−3. In recent years, with the increasing demand for power supply in harsh environments, high temperature-resistant dielectrics have attracted more and more attention. However, polymer-based composites with high glass-transition-temperature polymers still suffer fillers’ homogeneous dispersion problems. In this work, polyetherimide (PEI)-based nanocomposites filled with modified BT nanoparticles were designed and prepared. The surface modifier is an organic dye, celestial blue, which contains ortho-hydroxyl functional groups capable of chelating with metal oxides and a conjugated molecular structure that is well compatible with the PEI polymer matrix. The nanocomposites mBT/PEI exhibit improved dielectric and energy storage performance. At 2 vol%, the maximum energy density reaches 4.2 J cm−3, which was 31 % higher than that of the nanocomposite BT/PEI without surface modification.