Fabrication and Characterization of Novel Hyperbranched Polyimides with Excellent Organosolubility, Thermal and Mechanical Properties

A series of amine-terminated and anhydride-terminated hyperbranched polyimides (HBPIs) were successfully prepared with various commercial dianhydrides and a novel BB2-type aromatic triamine, 2,4,6-tris[4-(4-aminophenoxy)phenyl]pyridine, with a symmetrical triaryl-substituted pyridine segment and prolonged flexible linkages. The chemical structure of the triamine monomer and the hyperbranched structure of the resulting polymers were verified by Fourier transform infrared spectroscopy and H-1-NMR spectroscopy. The resulting HBPIs, which mainly held an amorphous morphology, exhibited improved organosolubilities in several strong polar aprotic solvents, good heat resistance with glass-transition temperature values in the range 218.6-311.0 degrees C, and excellent thermal stabilities in both N-2 and air [the temperature at 5% weight loss (T-5%) in N-2 was higher than 529.8 degrees C and the T-5% in air was higher than 465.1 degrees C]. The obtained HBPI films also showed outstanding mechanical properties with tensile strength, tensile modulus, and elongation at break values of 86.4-101.3 MPa, 1.73-2.04 GPa, and 5.07-10.67%, respectively; considerable optical transparency; low water absorption; and neutral interface wettability. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41544.