Biobased Benzoxazine Derived from Daidzein and Furfurylamine: Microwave-Assisted Synthesis and Thermal Properties Investigation

A biobased benzoxazine resin (Dz-f) demonstrating excellent thermal properties was synthesized from daidzein and furfurylamine by using a microwave heating method. The chemical structure of synthesized benzoxazine monomer was identified by FTIR and NMR (¹ H and ¹³ C NMR) before it was cured and its thermal properties evaluated by differential scanning calorimetry (DSC), TGA, and dynamic mechanical analysis (DMA). The cured resin p(Dz-f) exhibited a glass transition temperature (T_g ) of 391 °C, a very high char yield of 68.7 %, and outstanding thermal stability; the T_g value obtained was the highest thermal stability value ever reported for polybenzoxazine with a high biobased content. Moreover, Dz-f demonstrated a satisfying processability, which was rare for the high-performance thermosetting resins. This work provided us with a new strategy for the preparation of high biocontent resins with excellent thermal properties. In addition, the combination of biobased feedstocks with a microwave-assisted heating method as well as the potential application of this approach in high-end fields might perpetuate remarkable progress towards the sustainable development of the polymeric industry.