Multifunctional polyimide films with superheat-resistance, low coefficient of thermal expansion and fluorescence performance

A series of novel aromatic polyimide (PI) films containing xanthone moiety was prepared through a two-step procedure, namely, the polymerization of 2,7-diaminoxanthone (2,7-DAX) and six aromatic anhydrides and thermal imidization. The solubility, thermal properties, dimensional stability, mechanical properties, and fluorescence performance of the resulting PI films were studied extensively. The PI-1 film prepared by Pyromellitic dianhydride (PMDA)/2,7-DAX has a glass transition temperature (Tg) of more than 450 °C, a coefficient of thermal expansion (CTE) of as low as 6.3 ppm K−1, 5% weight loss temperature (T5) of 608 °C, a tensile strength of 164 MPa, and a tensile modulus of 5.65 GPa, resulting in potential applications in the flexible OLED field. In addition, xanthone moiety acts as a fluorophore group to provide a polymer fluorescent performance, and the maximum emission wavelength is in the range of 443–552 nm, from blue color to yellow color.