Design and applications of functional polyimides: Low-k engineering and carbon-based energy storage

This comprehensive review systematically examines the recent advancements in polyimide (PI) materials for high-frequency and high-power applications, emphasizing their synthesis, thermal conduction mechanisms, and functional modifications. The article elucidates the tunability of PI properties through diverse synthesis methodologies, including solution-based one-step, two-step, and three-step processes, as well as solvent-free melt polymerization. A critical analysis of thermal conductivity mechanisms highlights the role of phonon scattering, chain alignment, and interfacial interactions in amorphous and crystalline polymer matrices. Strategies to enhance intrinsic thermal conductivity, such as molecular chain orientation, hydrogen bonding, and liquid crystal epoxy integration, are thoroughly discussed. Furthermore, the review addresses the development of low-dielectric PI materials via fluorination, porous structuring, and bulky group incorporation, achieving dielectric constants as low as 1.76 while balancing mechanical integrity. In energy storage, PI-derived carbons and composites demonstrate exceptional electrochemical performance in supercapacitors, with specific capacitances up to 387.6 F g −1 and robust cycling stability. Innovations like laser writing carbonization and hybrid electrodes underscore PI’s versatility in flexible electronics. This work consolidates critical insights into structure-property relationships, offering a roadmap for designing next-generation PI-based materials tailored for advanced microelectronics, thermal management, and energy storage systems.