Synthesis of benzophenone-center bisphenol-A containing phthalonitrile monomer (BBaph) and its copolymerization with P-a benzoxazine

The benzophenone-center bisphenol-A containing phthalonitrile monomer (BBaph) was successfully produced by a nucleophilic substitution reaction of 4,4′-difluorobenzophenone with 4-nitrophthalonitrile and bisphenol-A in the presence of potassium carbonate. The chemical structure of the synthesized monomer was confirmed by 1H nuclear magnetic resonance (1H NMR), 13C NMR, and Fourier transform infrared spectroscopy (FTIR). The curing study of monomer was evaluated by the FTIR and DSC curves. The poly(BBaph) was subjected to gamma-ray irradiation with 100 kGy dose of 60Co gamma radiation. The variation in chemical structure, mechanical, thermomechanical and thermal properties of poly(BBaph) was evaluated by FTIR, flexural, dynamic mechanical analysis (DMA), and thermogravimetric analysis (TGA), respectively. All results confirmed very minute deviation in the estimated properties before and after radiation. The BBaph monomer was blended with typical mono-functional benzoxazine (P-a) in different weight ratios. The DSC, DMA, and TGA tests were performed to study the properties of copolymers. The high glass transition temperature (164-227 °C), and stiffness values (2.72-3.03 GPa) was observed for the copolymers. The thermal stability was also improved after the loading of BBaph in P-a, recorded values were in the range of 367-408 °C, and 46.1-58.7% for 5% weight loss temperature and char yield at 800 °C, respectively.