Novel benzoxazine monomer containing diacetylene linkage: An approach to benzoxazine thermosets with low polymerization temperature without added initiators or catalysts

A novel benzoxazine monomer containing diacetylene linkage has been synthesized by applying an oxidative coupling approach. The structure is confirmed by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Differential scanning calorimetry (DSC) is used to study crosslinking behavior of synthesized material. The benzoxazine monomer exhibits unexpectedly low exothermic peak with the onset around 140 °C, which is significantly lower than conventional benzoxazines or benzoxazines containing additional crosslinking sites. Benzoxazine polymerization at this low temperature is also confirmed by FTIR. The initial model studies are made in order to understand this phenomenon and preliminary explanation is given. High thermal stability of the crosslinked thermoset was confirmed by thermogravimetric analysis (TGA).