3,4-dihydro-3-phenyl-2H-1,3-benzoxazines derived from phenol-, resorcinol-, and phloroglucinol give monomers with one, two, and three oxazine units at a single benzene ring, respectively. Aside from the synthesis and characterization of such multifunctional benzoxazines, reactivity and polymerization behavior is studied in dependence of the oxazine functionality. Monomer reactivities are directly related to the number of oxazine functionalities present at the benzene ring yielding the lowest polymerization temperature for the trifunctional phloroglucinol-based benzoxazine. Comparing the polymerization processes and resulting structures, the trifunctional benzoxazine derivative enter new polymerization pathways, which include methylene linkages bridging aniline units, as well as the formation of carbonyl-derived structures.
Keywords: benzoxazine; polybenzoxazine; ring-opening polymerization; thermosets.