Incorporating bis‐benzimidazole into polyimide chains for effectively improving thermal resistance and dimensional stability

Abstract Heteroaromatic 6,6′‐bis[2‐(4‐aminobenzene)benzimidazole] and its corresponding copolyimides were synthesized to produce high temperature resistant polyimides (PIs). Due to the rigidity and aromaticity of heterocyclic bis‐benzimidazole, and the increased hydrogen bonding interactions, these PIs were found to have a high glass transition temperature ( T g ) over 457 °C, which also guarantees a better dimensional stability with a coefficient of thermal expansion (CTE) lower than 10 ppm K −1 in a wider temperature range of 50–400 °C. In addition, the PIs exhibit excellent thermal stability (5% weight loss temperature higher than 559 °C) along with outstanding mechanical properties. This study demonstrates the viability to access PIs with ultrahigh T g and low CTE in a wider range of temperature by the incorporation of bis‐benzimidazole moieties. © 2019 Society of Chemical Industry