Synthesis and characterization of naphthoxazine functional poly(ε-caprolactone)

A novel naphthoxazine ring-containing poly(ε-caprolactone) (PCL) was synthesized and characterized. For this purpose, first hydroxyl functional naphthoxazine, namely 2-(1H-naphtho[1,2-e][1,3]oxazin-2-yl)-ethanol (N-a-OH) was prepared by the reaction of 2-naphthol, ethanolamine and paraformaldehyde either in bulk or in dioxane as solvent at 110 °C. Subsequently, N-a-OH was used as the coinitiator for the stannous-2-ethylhexanoate (Sn(Oct)₂) catalyzed living ring-opening polymerization of ε-caprolactone. The GPC, IR, ¹H NMR, UV, and fluorescence spectroscopic studies revealed that low-polydispersity PCL with naphthoxazine functionality at the end of the chain was obtained. The resulting PCL macromonomer undergoes thermal curing in the presence of low molar mass benzoxazine (P-a) at various temperatures with the formation of thermosets having PCL segments.