Add time:07/18/2019         Source:sciencedirect.com

Novel diamine monomer 4,4′-bis((4-aminophenoxy)methyl)-1,1′-biphenyl (B4AP) was synthesized from precursor dinitro compound 4,4′-bis((4-nitrophenoxy)methyl)-1,1′-biphenyl (B4NP). A new series of polyimides was developed by condensation of B4AP with three dianhydrides (BTDA, ODPA, 6FDA). 4,4ʹ-methylenedianiline (MDA) was incorporated within the backbone of afore-synthesized polyimides for the preparation of copolyimides. Structural elucidations were carried out by FTIR and NMR (1H, 13C) spectroscopic techniques along with single crystal X-ray diffraction analysis, while TGA (dynamic and isothermal) and WAXRD techniques were used for properties evaluations of polymers. The crystal systems of B4NP and B4AP were found to adopt the space group P-1 and P21/c respectively. Polyimides showed substantially high thermal stability as their decomposition started around 400 °C. Execution of copolymerization strategy with MDA further enhanced their thermal stability. The temperature at 5% weight loss (T5) of polyimides under nitrogen atmosphere was in the range of 459–516 °C which increased to 496–538 °C for copolyimides. Air accelerated decomposition above 550 °C. Isothermal TGA disclosed that copolyimides are capable to withstand elevated temperatures for long time.

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