High performance combustion synthesis-based low-temperature curing of benzoxazine

Polybenzoxazine resins are a new type of high-performance thermosetting resins with excellent properties. However, their high curing temperature significantly limits their applications. In this study, precursor catalysts with high catalytic efficiency were prepared using different transition metal nitrates and acetylacetone. Leveraging the principle of the combustion synthesis method, we successfully reduced the curing temperature of benzoxazine while simultaneously enhancing its mechanical and anticorrosive properties. The results demonstrated that this approach lowered the initial curing temperature of fluorinated benzoxazines to below 100 °C and significantly improved their adhesion and hardness, achieving ratings of 5B and 6H, respectively. In addition, the impedance modulus of the Ga(NO 3 ) 3 /AcAcH/benzoxazine system reached 2.17 × 10 5  Ω cm −2 , while the In(NO 3 ) 3 /AcAcH/benzoxazine system exhibited an impedance modulus of 7.45 × 10 4  Ω cm −2 , significantly enhancing corrosion resistance compared to the pure benzoxazine coating. The In(NO 3 ) 3 /AcAcH/benzoxazine system ultimately formed a heterogeneous domain structure. In contrast, the Ga(NO 3 ) 3 /AcAcH/benzoxazine system resulted in a homogeneous domain structure with minimal free volume. This study presents a novel and efficient strategy for reducing the curing temperature and improving the mechanical performance of benzoxazine, offering a simple yet effective catalytic approach with potential for applications in anticorrosion coatings.