Design and characterization of novel organometallic benzoxazine monomer with aluminum incorporation

In this study, a new organometallic benzoxazine monomer (BA-Al) was synthesized by incorporating an aluminum (Al) atom into the structure of bisphenol A (BPA) to obtain the Al-BPA molecule. The BA-Al monomer was then synthesized through a one-step Mannich reaction. The molecular structure of Al-BPA was confirmed by proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared spectroscopy (FTIR), revealing new peaks in the 1 H NMR spectrum due to the formation of Al-O bonds. The FTIR spectra also showed the characteristic Al-O vibration bands. For the BA-Al monomer FTIR analysis confirmed the presence of benzoxazine rings with characteristic bands. Additionally, peaks were associated with Al-O bonds. 1 H NMR analysis further confirmed the BA-Al structure, providing evidence for the presence of the oxazine ring. DSC analysis showed that BA-Al cures at a lower temperature compared to BA-a, likely due to the influence of aluminum. The TGA analysis of P(BA-Al) indicated significant degradation, while P(BA-a) starts decomposing at a higher temperature. Dynamic mechanical analysis (DMA) analysis revealed that P(BA-Al) has a lower storage modulus and glass transition temperature compared to P(BA-a). Monotonic tensile tests showed that both P(BA-a) and P(BA-Al) exhibit similar tensile strength and elongation trends at varying strain rates, but P(BA-a) consistently shows slightly higher ductility. Solubility tests indicated that both BA-a and BA-Al monomers exhibit good solubility in polar aprotic solvents, while the corresponding polymers show reduced solubility, with P(BA-Al) being more soluble in DMF and DMSO. Electrical conductivity measurements showed that Al-BPA has a conductivity of 89.92 S/m, BA-Al has a conductivity of 67.98 S/m, while BA-a exhibited negligible conductivity. This suggests that aluminum content plays a crucial role in enhancing electrical conductivity. The synthesized BA-Al monomer demonstrates promising properties for specialized applications, particularly in the field of electromagnetic protection.