Furan-derived biobased polybenzoxazines with intrinsic flame retardancy and high thermal stability

Abstract

With the global shortage of petroleum-sourced raw materials and the strengthening of the sustainable development concept, developing high-performance thermosetting resins from renewable biomass remains a challenge. Benzoxazine resin is a new type of thermosetting resin that has potential applications in many emerging fields. Here, two bifunctional biobased benzoxazine monomers (D-IEU-FA and D-IEU-SA) containing double bonds in centrosomes were easily synthesized from renewable isoeugenol with biobased furfurylamine and stearylamine. The chemical structures of both monomers were clearly characterized, and their curing behaviors were investigated in detail. After ring-opening thermal polymerization, biobased polybenzoxazines (poly(D-IEU-FA) and poly(D-IEU-SA)) were successfully prepared. Both polybenzoxazines exhibited good thermal stability. The 5% weight loss temperatures of poly(D-IEU-FA) and poly(D-IEU-SA) were 406 and 368 °C , respectively. The reactive furan structure and bifunctional oxazine in D-IEU-FA endowed poly(D-IEU-FA) with higher rigidity and crosslinking density. The glass transition temperature of poly(D-IEU-FA) was above 350 °C , much higher than that of poly(D-IEU-SA) (210 °C ). Furthermore, poly(D-IEU-FA) also exhibited good thermal dimensional stability with a low coefficient of thermal expansion (76 ppm K⁻¹). In particular, poly(D-IEU-FA) showed excellent intrinsic flame-retardant performance with low heat release capacity (28 J g⁻¹ K⁻¹) and low total heat release (0.9 kJ g⁻¹). These results indicated that this new type of biobased polybenzoxazine could be expected to be a potential candidate for application as a high-performance engineering material.