Polyimide-Based Nanocomposites with Ultra-High Dielectric Breakdown Strength: A Review and New Record

A novel state-of-the-art record in the field of dielectric breakdown strength enhancement of polyimide-based nanocomposites is reported in this work. This achievement has been obtained through accurate optimization of the surface chemistry of silica (SiO₂) nanoparticles. An efficient surface functionalization using 3-aminopropyltriethoxysilane (APTES) enabled the successful grafting of a single-layer ligand coverage onto SiO₂ and to reach an optimal colloidal stability, promoting their homogeneous dispersion within the PI matrix. APTES-functionalized PI/SiO₂ nanocomposite films exhibit significant improvements of the electrical insulation properties with lower permittivity, dielectric loss, and conductivity under high electric field, all related to more efficient dipolar motion restrictions and charge trapping effects. This study demonstrates for the very first time the path to design revolutionary ultrahigh breakdown field strength properties in a polyimide-based nanocomposite with E_BD ∼ 1000 V/μm and an enhancement factor η_E ∼68% compared to pure PI. Our results present a methodology for significantly advancing the state-of-the-art, enabling polyimide-based nanocomposite films to unlock future high-voltage applications, such as integrated insulation and capacitive energy storage.