Synthesis and characterization of melt‐processable polyimides derived from diaminodiphenylsulfone and benzophenone tetracarboxylic dianhydride with excellent heat resistance and thermoplasticity

Abstract Polyimide has excellent heat resistance, dielectric properties, and mechanical properties, and has a wide range of applications in aerospace, electronic packaging, and insulating materials. However, traditional polyimide is difficult to melt and dissolve, and its processing is difficult, which has become an important reason limiting its practical application. Therefore, the development of high temperature‐resistant thermoplastic polyimide has become a research hotspot. To prepare high temperature‐resistant thermoplastic polyimide materials, a series of thermoplastic polyimides was successfully prepared using 3,3′,4,4′‐benzophenone tetracarboxylic dianhydride, 3,3′‐diaminodiphenylsulfone, 2,3′,3,4′‐benzophenone tetracarboxylic dianhydride, 9,9‐bis(4‐aminophenyl)fluorene, and 2,2‐bis(3‐amino‐4‐hydroxyphenyl)hexafluoropropane via a two‐step method. The effects of non‐coplanar structure and bulky groups on the solubility, processability, and thermal properties of polyimide were studied. The structure, heat resistance and thermoplasticity of polyimide were characterized via various methods. The results show that the glass transition temperature of the prepared thermoplastic polyimide is between 292 and 302°C, and has excellent thermal resistance. The processing viscosity of polyimides is as low as 9210 Pa.s, and it has a certain degree of processing properties. It may be designed to be used in high temperature‐resistant hot melt adhesives for structural components, high temperature‐resistant melt processing resins, or thermoplastic composite materials used in the field of aerospace in the future.