Correlating the dielectric properties with chain packing density of polar functionalities in hyperbranched polyimides
Polymer-based dielectric materials with high energy density and thermal stability are critical for modern electric/electronic industries. Polyimide (PI) based materials are promising due to their high temperature resistance and chemical inertness, yet their inherently low dielectric constant and limited charge-discharge energy density restrict applications in film capacitors. While incorporating ferroelectric or conductive fillers can enhance dielectric performance, batch-to-batch inconsistency and physical deterioration remain problematic. This study focuses on molecular structure design and modulation, preparing hyperbranched polyimides with different dianhydride monomers and branching degrees. The effects of chain packing density with polar groups on dielectric and energy storage performances were systematically investigated via experimentation and molecular simulation. Results demonstrate a significant correlation between monomers' electrical distribution and packing density in polymer systems. Molecular simulation further elucidated the underlying mechanism. This work establishes a foundation for designing polymer-based dielectric materials with high dielectric and energy storage performances at the molecular level.