Mechanical, thermal, and optical properties of yellow fluorescent molecule/polyimide composite films

In recent years, polyimides (PIs) with fluorescent properties have attracted special attention. In this study, the yellow fluorescent compound 2-(4-(diphenylamino)benzylidene)malononitrile (Y) was synthesized. Then, a series of yellow fluorescent molecule/polyimide composite films were prepared using 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (6FAPB) and 1,2,3,4-cyclobutane tetracarboxylic dianhydride (CBDA) as the monomers, followed by thermal imidization. To explore the structures and properties, the obtained PI(6FAPB-CBDA)-Y composite films were characterized in detail. The test results showed that as the Y content increased from 0% to 1.2%, the glass transition temperature ( T g ) of the PI(6FAPB-CBDA)-Y composite films decreased from 328°C to 308°C, and the tensile strength declined from 119.1 MPa to 78.4 MPa. When the Y ratio reached 1.2%, the PI(6FAPB-CBDA)-1.2Y film exhibited an optimal fluorescence performance, along with excellent stability. Additionally, all the composite films maintained good transparency and were soluble in some polar aprotic solvents. In brief, the PI(6FAPB-CBDA)-Y composite films demonstrate outstanding comprehensive properties, making them suitable for applications in anti-counterfeiting, optoelectronic devices, and smart responsive materials.