DFT-Guided Design of Functional Polyimide Chromophores: Group Assembly Strategies for Environmentally Robust Full-Color Systems

With the rapid development of optical engineering, colored polyimides (PIs) have emerged as critical materials. However, the lack of design methodology has hindered the rational systematic exploration of colored PI. To fill the gap, a molecular engineering scheme based on DFT-assisted spectral screening (Density functional theory, DFT) has been proposed, and three colored diamines screened out from anthraquinone and azobenzene derivatives were validated to be optimal three primary-color monomers (magenta, yellow, and cyan). A small amount of these colored diamines as chromophores was copolymerized with representative colorless transparent polyimide monomers, 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA) and 2,2′-bis(trifluoromethyl)benzidine (TFMB) to obtain three monochromatic PIs, respectively. The chromatic gamut of polyimide films was then systematically expanded through proportional blending of trichromatic PIs, enabling full-spectrum color accessibility. Furthermore, a predictive mathematical model correlating colorimetric parameters ( L *, a *, b *) with ternary composition ratios was formulated based on the subtractive color principle. Experimental results show that the engineered colored polyimides maintained intrinsic thermal and mechanical properties while demonstrating exceptional chromatic stability under thermal cycling and accelerated UV aging. The methodology, characterized by simplicity, universal applicability, nondamaging performance, and methodological robustness, establishes a technologically reliable pathway for industrial-scale production of performance-preserved colored polyimides.