Aromatic dialdehyde-based bisbenzoxazines: The influence of relative position of oxazine rings

Polybenzoxazines are known to have superior thermal stability. Especially, the use of aromatic aldehydes instead formaldehyde for synthesis benzoxazines monomers could improve this However, increase in content monomer can prevent processability. The objective article is understand relationships between conformation an dialdehyde and its properties. Two benzoxazine were synthesized, based on salicylaldehyde, furfurylamine respectively terephthalaldehyde (TPA, para configuration) isophthalaldehyde (IPA, meta). Structural characterizations showed differences intramolecular interactions two isomers. melting transition “meta” isomer was 50 °C lower than “para” monomer, whereas polymerization temperatures enthalpies nearly same. Volatile compounds released during same both cases, as investigated by mass spectrometry (Py-GC/MS). Curing kinetics using model-free kinetic methods revealed that E-dependency follows trend monomers. Finally, degradation monitored thermogravimetric analysis under inert atmosphere similar, with high char yields (64%).