Facile synthesis of soluble, self-crosslinkable and crystalline polyimides with ultrahigh thermal/chemical resistance

Low-cost and processable polyimides with ultrahigh thermal/chemical stability is urgently demanded in microelectronic and aeronautics/astronautics industries. In this work, crystalline polyimides containing reactive cyano groups were synthesized from readily available monomers by facile one-step solution polycondensation method. The obtained polyimides are soluble at room temperature in the common solvents, and can be easily made into transparent polymer films. After curing, the resultant products become completely insoluble in any solvents, exhibiting excellent chemical stability. The glass transition temperature (Tg) and 5% thermal decomposition temperature (T5) for the cured polyimides are as high as 462 °C and 570 °C, respectively. The ultrahigh Tg and T5 together with good solubility are superior to most polyimides already reported in the literature. Moreover, the polyimide films are quite tough with the tensile strengths of 94–118 MPa, Young's moduli of 2.3–2.7 GPa and elongations at break of 5.3%–8.6%. The combination of facile synthesis method, solution-proccesability, excellent thermal/chemical resistance and mechanical property endows the polymers with promising applications in polymer films and composite materials.