Improving comprehensive performance of norbornene‐furan functionalized benzoxazine resins by regulating the bridge length.

In this study, we designed and synthesized a series of norbornene‐furan functionalized benzoxazine monomers (HPAP‐fa, HPAMP‐fa, and HPTM‐fa) by regulating the bridge length in benzoxazine structure in order to improve the comprehensive performance of norbornene‐furan functionalized benzoxazine system. This research systematically examined the impact of flexible segments on the structural information, polymerization behaviors, thermal stability, and flame retardancy of resulting polybenzoxazines. Initially, the structural characteristics of benzoxazine were confirmed through nuclear magnetic resonance, Fourier‐transform infrared (FT‐IR), and HR‐MS. Subsequently, the polymerization mechanisms of each benzoxazine monomer were investigated utilizing differential scanning calorimeter and in situ FT‐IR analyses. Finally, the thermal stability and flame‐retardant properties were investigated by TGA and micro‐combustion calorimetry measurements. Consequently, HPAP‐fa exhibited the lowest polymerization temperature and the corresponding poly(HPAP‐fa) showed very high thermal stability (Td5 of 392°C and Td10 of 437°C) as well as excellent flame retardancy (HRC of 83.7 J g−1 K−1), which shows a significant improvement compared to poly(HPTM‐fa). As a result, the modulation of bridge segments within the monomer represents a viable approach towards enhancing the holistic efficacy of norbornene‐furan functionalized benzoxazine systems. [ABSTRACT FROM AUTHOR]