Tailoring Molecular Structures of Polyimides for Frontier Applications.

Abstract

Polyimides (PIs) are widely used in frontier technologies because they combine properties that are difficult to achieve in other polymers, including high thermal stability with processability, mechanical robustness with dimensional stability, and electrical insulation with chemical resistance. In emerging applications, additional functions such as optical transparency, photosensitivity, or thermal insulation are required without compromising long-term reliability. This versatility arises from the structural tunability of PI chemistry around the imide backbone. By adjusting backbone rigidity, polarity, and free volume, incorporating fluorinated or alicyclic units, introducing crosslinkable end-groups, and adopting organic-inorganic hybrid motifs, PI systems can be tailored for diverse processing routes and material forms, including thermosetting resins for composites, engineering plastics, porous foams and aerogels, high-performance films and coatings, and photosensitive polyimides (PSPIs) for electronic packaging. Across these applications, structure-processing-property relationships, where molecular design defines the processing window and the processing route determines the dominant performance targets, provide a common framework for tailoring PI materials from aerospace assemblies to wafer-level packaging.