Novel high Tg, organosoluble poly(ether imide)s containing 4,5-diazafluorene unit: Synthesis and characterization

• The 4,5-diazafluorene unit was introduced into the polyimides backbone.
• The polymers showed good solubility and high glass transition temperatures.
• The polymers with 4,5-diazafluorene units show a promising potential application.

The synthesis of aromatic poly(ether imide)s containing 4,5-diazafluorene units in the polymer backbone is described. 9,9-di[4-(4-Aminophenoxy)phenylene]-4,5-diazafluorene (3), which was used as a new monomer, was synthesized with 4,5-diazafluoren-9-one as the starting material. This diamine monomer was employed in reactions with a variety of aromatic dianhydrides to furnish poly(ether imide)s. These 4,5-diazafluorene-based polymers showed solubility in polar amidic solvents such as NMP, DMAc and DMF, good optical transparency, and high thermal stability. The glass transition temperatures (Tg) of these poly(ether imide)s were recorded between 325 and 356 °C with the help of differential scanning calorimetry (DSC), and the Tg determined by dynamic mechanical thermal analyses (DMA) stayed in the range of 329–363 °C, and the 10% weight-loss temperatures all occurred above 560 °C in both nitrogen and air atmospheres. In addition, the flexible polyimide films possessed tensile strengths in the range of 64–101 MPa, tensile modulus of 1.8–2.1 GPa, and elongations at break of 6–13%.

9,9-di[4-(4-aminophenoxy)phenylene]-4,5-diazafluorene has been synthesized as a new cardo structure and the properties of poly(ether imide)s containing 4,5-diazafluorene unit are examined in detail. These 4,5-diazafluorene-based polymers showed solubility in polar amidic solvents such as NMP, DMAc, DMF at room temperature, good optical transparency, and high thermal stability. The incorporation of 4,5-diazafluorene units into the polymer backbone leads to polymeric materials with high Tg that are amenable for use as high-performance materials and demonstrates a promising potential for future application.Figure optionsDownload as PowerPoint slide