A straightforward synthetic approach to incorporate a hydrogen-bonding motif as part of a fully bio-based benzoxazine monomer (NAR-fa) is developed, leading to the first latent catalyst-containing thermosetting resin derived from natural renewable resources. The acronym is derived from the phenol (naringenin) and amine (furfurylamine) used in the synthesis. Interestingly, the newly developed benzoxazine resin exhibits a long shelf life in spite of possessing the lowest polymerization temperature reported hitherto for pure benzoxazines, 166 °C. The hydrogen-bonding motif is identified as an important design feature for studying the thermal behavior of the resin. All most common thermal and fire related properties, such as the glass transition temperature (T_g), temperature at which the weight loss is 5 and 10% (T_d5 and T_d10), char yield (Y_c), limiting oxygen index (LOI), heat release capacity (HRC), and total heat released (THR), were far superior to those of typical polybenzoxazines. As a natural consequence of these great characteristics, NAR-fa was applied in small amounts (5 mol%) as an initiator and a property modifier of other petroleum-based and natural renewable resourced benzoxazine-based systems. The thermal properties of the resulting copolymeric thermosets were maintained or slightly enhanced, while those related to fire improved by about 38 and 51% for THR and HRC, respectively. These results highlight the utility of the latent catalyst-containing resin design derived from natural renewable resources in the preparation of high-performance resins and thermosets.

In this study we used a facile approach to synthesize poly(benzoxazine-co-imide-co-siloxane) (oHPNI-oda-PDMS), a new main chain-type copolymer featuring benzoxazine, imide, and siloxane units as repeating units. In contrast to previously reported polydimethylsiloxane (PDMS)-containing benzoxazine resins, oHPNI-oda-PDMS was formed directly through hydrosilylation of an ortho-norbornene functionalized bisbenzoxazine monomer (oHPNI-oda) and PDMS. Nuclear magnetic resonance and Fourier transform infrared (FTIR) spectroscopy confirmed the chemical structures of oHPNI-oda and oHPNI-oda-PDMS. We used differential scanning calorimetry and in situ FTIR spectroscopy to investigate the polymerization behavior of both the benzoxazine monomer and the copolymer, and used dynamic mechanical analysis, thermogravimetric analysis, and microscale combustion calorimetry to determine the thermal properties and flame retardancy of the cross-linked polybenzoxazines. The polybenzoxazine derived from oHPNI-oda-PDMS possessed an excellent combination of properties—high thermal stability, low flammability, and very low dielectric constants (k = 2.36–2.29)—suggesting many potential applications in aerospace, microelectronics, and flame-resistant materials.