Two novel benzoxazine monomers containing allyl groups:  3-allyl-3,4-dihydro-2H-1,3-benzoxazine and bis(3-allyl-3,4-dihydro-2H-1,3-benzoxazinyl)isopropane have been synthesized from phenol and Bisphenol A with allylamine and formaldehyde. Their DSC exhibit two exotherms at ca. 145 °C and at ca. 220 °C which correspond to allyl and oxazine thermal polymerization, respectively. Both monomers undergo thermal cure with the formation of thermosets having excellent thermomechanical properties. These thermosets exhibit higher T g (ca. 300 °C), maintain their storage moduli at higher temperature, and have better thermal stability than the corresponding polybenzoxazines without allyl groups.

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Novel benzoxazine monomers containing arylpropargyl ether were prepared, and highly thermally stable polybenzoxazines were obtained by the thermal cure of the monomers. One monomer is a monofunctional benzoxazine, 4-propargyloxyphenyl- 3,4-dihydro-2 H -1,3-benzoxazine (P-appe), and the other is a bifunctional benzoxazine, bis(4-propargyloxyphenyl-3,4-dihydro-2 H -1,3-benzoxazinyl)isopropane (B-appe). The chemical structures of these novel monomers were confirmed by IR and 1H NMR. The cure behavior of the monomers, P-appe and B-appe, and the properties of the resulting polymers were studied in comparison with 4-phenyl-3,4-dihydro-2 H -1,3-benzoxazine (P-a) and bis(4-phenyl-3,4-dihydro-2 H -1,3-benzoxazinyl)isopropane (B-a) as typical benzoxazine monomers without propargyl groups. DSC cure of both P-appe and B-appe showed a single exotherm corresponding to the ring-opening polymerization of oxazine ring and cross-linking of arylpropargyl ether group at almost the same temperature range as P-a and B-a. The T g values of polybenzoxazines derived from propargyl-containing monomers, PP-appe and PB-appe, were higher by ca. 100 and 140 °C than those of typical polybenzoxazines without propargyl groups, PP-a and PB-a, respectively. The storage moduli of PP-appe and PB-appe were maintained constant up to higher temperature for ca. 100 °C than that of PP-a and PB-a. The higher thermal stability of the novel polybenzoxazines, PP-appe and PB-appe, than that of the typical polybenzoxazines, PP-a and PB-a, was proved from thermogravimetric analyses.

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