Thermally activated polymerization behavior of bisphenol‐S/methylamine‐based benzoxazine

A bifunctional benzoxazine monomer, 6,6′‐bis(3‐methyl‐3,4‐dihydro‐2H‐benzoe] 1,3]oxazinyl) sulfone (BS‐m), was synthesized from bisphenol‐S, methylamine, and formaldehyde via a solution method. The chemical structure of BS‐m was characterized with ¹H and ¹³C‐nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and elemental analysis. The ring‐opening polymerization reaction of BS‐m monomer was studied by FTIR, ¹³C solid‐state NMR, and differential scanning calorimetry. With the polymerization reaction proceeding, the intensities of the FTIR absorption peaks of CH₂, C? O? C, and C? N? C of the oxazine ring decreased gradually, and some of these absorption peaks disappeared. The shapes and intensities of the absorption peaks associated with benzene ring, sulfone group, and aromatic C? S bond changed in various ways. The changes in the solid‐state ¹³C‐NMR pattern, including chemical shifts, intensity of resonances, and line‐width, were observed from the spectra of BS‐m and the corresponding polybenzoxazine. The melting process of BS‐m overlapped with the beginning of the ring‐opening polymerization reaction. The polymerization kinetic parameters were evaluated for nonisothermal and isothermal polymerization of BS‐m. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012