Synthesis and Properties of Benzoxazine Monomers Bearing Both 3-Methyltetrahydrophtalimide and Nitrile Groups: Para-Para vs. Ortho-Ortho

Two 3-methytetrahydrophtalimide-functional benzoxazine monomers containing nitrile group have been prepared in order to achieve the basic design rules for developing high-performance thermosets via multifunctional benzoxazines. The chemical structures of the two new synthesized benzoxazine monomers have been confirmed by H-1 NMR, C-13 NMR and FT-IR. Besides, the polymerization behavior has been studied by using DSC and in situ FT-IR. In addition, the thermal stability and flame retardant properties of the resulting polybenzoxazines have also been investigated using TGA and MCC. The polybenzoxazine based on ortho-3-methytetrahydrophtalimide functional benzoxazine containing ortho-nitrile group exhibits excellent thermal stability and low flammability, with a T-d10 of 378 degrees C and a HRC value of 180 J/(g K).