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SUMMARY:The benzoxazine monomer synthesis via 1,3,5-trialkyl(aryl)hexahydro-1,3,5-triazine intermediate is followed by 1 H NMR, FT-IR, and SEC. A model compound, 1,3,5-triphenylhexahydro-1,3,5-triazine, is synthesized independently and its reaction with bisphenol-A and paraformaldehyde in stoichiometric amounts is also followed by 1 H NMR. Additional model compounds, 1,3,5-trimethyl(ethyl)hexahydro-1,3,5-triazine, are used instead of a primary amine to synthesize bifunctional benzoxazine monomers, bis(3,4-dihydro-2H-3-methyl(ethyl)-1,3-benzoxazinyl)isopropane, via novel solventless reaction with bisphenol-A in the presence of paraformaldehyde. The mechanism of this reaction is proposed.

Dynamic mechanical analysis is performed on polybenzoxazines from acetylene-terminated benzoxazine monomers, and glass transition temperatures of these polybenzoxazines are found in the range of 329 -368°C. It has been identified that the high glass transition temperature and high thermal stability are due to polymerization of the acetylene terminal group, in addition to oxazine ring polymerization through a comparison study with analogous polybenzoxazines that are obtained from monomers without an acetylene functional group.