(177m) Challenge for Trade-Off Relationship between Mechanical Property and Healing Efficiency of Self-Healable Polyimide

Colorless polyimides (CPIs) with outstanding mechanical properties are used as essential materials in the production of future flexible display panels, foldable windows, and spacecraft cockpit materials. Particularly, with the recent release of foldable and rollable smartphones, CPI application in smartphone products has heightened expectations. However, fatigue fractures caused by repetitive stress, deformation, and microcracks may critically determine the material's properties and lifespan. To address this issue, this study developed a self-healing CPI that rapidly and efficiently restores transparency and repairs damage caused by external stress. By adjusting the ratio of healable disulfide bond monomers to aliphatic diamine monomers and optimizing the diamine components, the glass transition temperature (Tg) was controlled to enable self-healing properties at relatively low temperatures. Fully aromatic imide structures typically exhibit high Tg due to strong interchain interactions that limit mobility. Thus, we prepared imides with four-component semi-aromatic structures by adjusting the contents of 4,4-(hexafluoroisopropylidene)diphthalic anhydride and 4,4-(4,4-isopropylidenediphenoxy)bis(phthalic anhydride) to yield novel, flexible, self-healable CPIs with excellent mechanical properties and low healing temperatures below 100°C. Moreover, the films maintained exceptional mechanical properties even after over 10,000 bending fatigue cycles, demonstrating their potential for advanced technological applications.