Synthesis of a novel benzoxazine precursor containing phenol hydroxyl groups and its polymer

A novel benzoxazine precursor containing phenol hydroxyl groups was synthesized from bisphenol A, 4,4′‐diaminodiphenyl methane, and formaldehyde with a molar ratio of 2:1:4. The benzoxazine precursor was characterized with Fourier transform infrared, proton nuclear magnetic resonance, and size exclusion chromatography. The curing reaction was monitored by the gel time, differential scanning calorimetry, and Fourier transform infrared. The obtained polybenzoxazine showed high thermal stability and a high glass‐transition temperature.