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Synthesis and thermally induced structural transformation of phthalimide and nitrile-functionalized benzoxazine: toward smart ortho-benzoxazine chemistry for low flammability thermosets
A novel ortho-phthalimide-functionalized benzoxazine monomer containing an ortho-nitrile group has been synthesized in order to further systematically evaluate the thermally induced structural transformation from benzoxazine resin to cross-linked polybenzoxazole. The chemical structure of the synthe...
Autores principales: | , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
The Royal Society of Chemistry
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9059662/ https://www.ncbi.nlm.nih.gov/pubmed/35518001 http://dx.doi.org/10.1039/c8ra10009h |
Sumario: | A novel ortho-phthalimide-functionalized benzoxazine monomer containing an ortho-nitrile group has been synthesized in order to further systematically evaluate the thermally induced structural transformation from benzoxazine resin to cross-linked polybenzoxazole. The chemical structure of the synthesized monomer has been confirmed by (1)H and (13)C nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. Also supporting the detailed structure is (1)H–(13)C heteronuclear multiple quantum coherence (HMQC), which identifies the local proton-carbon proximities. The polymerization behaviors, including the ring-opening polymerization of the oxazine rings and the cyclotrimerization of the nitrile functionalities, are studied by differential scanning calorimetry (DSC) and in situ FT-IR. In addition, the subsequent benzoxazole formation after polymerization has also been analyzed using thermogravimetric analysis (TGA) and magic-angle spinning (MAS) solid-state (13)C NMR. The resulting cross-linked polybenzoxazole derived from the benzoxazine monomer exhibits exceptionally high thermal stability and low flammability, with an extremely high T(d5) temperature (550 °C), a high char yield value (70%) and an extraordinarily low total heat release (THR of 7.6 kJ g(−1)). |
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