Novel fluorinated hyperbranched polyimides with excellent thermal stability, UV-shielding property, organosolubility, and low dielectric constants

A novel fluorinated aromatic triamine, named 1,3,5-tris (4-(2-trifluoromethyl-4-aminophenoxy)phenyl) benzene (TTFA-POPB), with several -CF3 groups, prolonged chain segments, and ether bonds was first successfully synthesized via a three-step reaction. Then a series of fluorinated hyperbranched polyimides (FHBPIs) with terminal amino or anhydride groups were prepared by condensation polymerization, which were derived from three commercial dianhydrides and the obtained triamine. The prepared FHBPIs showed excellent optical properties with the transmittance reaching 94.5% at 800 nm, favorable ultraviolet (UV)-shielding property with only 27% photodegradation of methylene blue solution after intense UV irradiation for 50 min, good thermal stability with glass transition temperature between 225 degrees C and 264 degrees C, and 10% weight loss temperature of 520-555 degrees C and 509-541 degrees C, respectively, in nitrogen and air atmosphere. They also exhibited relatively good mechanical properties with tensile strength, tensile modulus, and elongation at break values of 64.2-84.2 MPa, 1.2-1.5 GPa, and 6-10%, respectively. Moreover, the introduction of -CF3 and hyperbranched architecture reduced the dielectric constants of the FHBPIs to 2.69-2.92 and increased the surface contact angles to more than 98 degrees. Thus, the FHBPIs are promising dielectric or UV-shielding materials.