4,4'-(9-Fluorenylidene)dianiline is primarily used in the production of high-performance polymers, particularly polyimides and epoxy resins. These polymers are valued for their thermal stability, mechanical strength, and chemical resistance, making them suitable for applications in the electronics industry, such as in the manufacture of flexible printed circuit boards and insulating coatings. Additionally, it serves as a key intermediate in the synthesis of advanced materials used in aerospace and automotive industries, where durability under extreme conditions is essential. Its role in enhancing the properties of polymers also extends to adhesives and coatings, providing improved performance in demanding environments.