Renewable biomass resources to access halogen- and phosphorus-free flame retardant thermosets with ultra-low heat release capacity

Developing high-performance thermosets with outstanding anti-flammability from sustainable resources has attracted increasing attention due to both safety and environmental concerns. Herein, a novel bio-based bis-benzoxazine thermosetting resin has been successfully synthesized via Mannich condensation reaction from paraformaldehyde and natural renewable resources, aesculetin and furfurylamine. Detailed information of the chemical structure for this bio-benzoxazine is analyzed by nuclear magnetic resonance (NMR) and Fourier transform infrared (FT-IR) spectroscopies, elemental analysis and high-resolution mass spectrometry (HR-MS). In addition, the resin polymerization behavior is investigated by differential scanning calorimetry (DSC) and in situ FT-IR analyses. Notably, the fully polymerized bio-thermoset shows high thermal stability with T d10 of 407 °C and T g of 261 °C, and extremely low flammability with heat release capacity (HRC) value of 2.51 J·g −1 ·K −1 and total heat release (THR) value of 0.78 kJ·g −1 . Overall, the current work provides a facile and sustainable synthetic route access to a series of halogen- and phosphorus-free nonflammable bio-thermosets based on smart benzoxazine chemistry.