Molecular design of Carborane-containing Polyimide copolymers: enhanced high-temperature resistance and tribological performance

Conventional polyimides (PI) suffer significant mass loss and performance degradation under prolonged high temperature exposure, limiting their utility in extreme thermal environments. This study employs a molecular-level design strategy to synthesize carborane-containing polyimide copolymer (BMCB/PI) via copolymerization of 1,7-bis(aminophenyl)-meta-carborane (BMCB) with 4,4′-oxydiphthalic anhydride (ODPA) and the flexible diamine 1,4-bis(4-aminophenoxy)benzene (TPE-Q). The 30BMCB/PI film demonstrates remarkable improvements in thermomechanical properties (T_d5% = 552.6 °C, Young's modulus = 2.17 GPa) compared to pure PI (494.6 °C, 1.63 GPa). Moreover, its unique high-temperature resistance mechanism enables an ultrahigh char yield (R_w) of 65.9% at 800 °C in air, indicating exceptional thermal stability. Notably, the 30BMCB/PI film also exhibited particularly excellent tribological properties, with a 54% reduction in specific wear rate under dry sliding conditions compared to pure PI. It can maintain excellent tribological properties even in high-temperature (100-400 °C) environments. This study achieves synergistic enhancement of thermal stability, mechanical properties, and tribological performance in polyimide materials through covalent incorporation of carborane structural units into the polyimide backbone, providing novel insights for designing high-performance polymers for high-temperature tribological applications.