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

摘要

A bifunctional benzoxazine monomer, 6,6a-bis(3-methyl-3,4-dihydro-2H- benzo[e] [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 ~(13)C-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, ~(13)C solid-state NMR, and differential scanning calorimetry. With the polymerization reaction proceeding, the intensities of the FTIR absorption peaks of CH _2, 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 ~(13)C-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.