Abstract: With substituted bisphenol A[2,2-bis(4-hydroxy-3-allylphenyl)propane], paraformaldehyde, and allylamine as the starting materials, a novel benzoxazine precursor without β-hydrogen is developed by a solventless procedure. The molecular structure is verified by FTIR, ¹HNMR, GPC and EA. It is confirmed that there are three reactive groups on the benzoxazine structure: N-allyl, Ar-allyl, benzoxazine ring. As the ortho and para positions on the phenol are occupied by different groups, it is quite significant to investigate the reaction of the three groups. So we synthesize some other kinds of benzoxazine, isothermal differential scanning calorimetry(DSC) and Fourier transform infrared(FTIR) are used to determine the detailed reactions of the three groups. It indicates that N-allyl and benzoxazine ring react nearly at the same temperature(about 246 ℃), and Ar-allyl reacts at about 350 ℃. Further more, with two different kinds of catalysts, the as-synthesized benzoxazine precursor is also studied by DSC and FTIR to determine the influence of the catalysts on curing. Among the catalysts tested, Lewis acids show promising results, while phenolic catalysts can also decrease the onset curing temperature of the benzoxazine ring. Choosing one sample catalyzed by TiCl₄, the curing reactions are discussed at different temperatures by FTIR and a mechanism of the benzoxazine precursor catalyzed by TiCl₄ is suggested.

Key words: β-Hydrogen, Benzoxazine, Allyl, Catalyzed curing, Mechanism