Synthesis of novel imide-functionalized fluorinated benzoxazines and properties of their thermosets

In this study, two novel imide-functionalized fluorinated benzoxazines, N,N′-bis(N-phenylacetylene-3,4-dihydro-2H-1,3-benzoxazinyl)-(4,4′-hexafluoroisopropylidene)bisphthalimide (6FIBZ-apa) and N,N′-bis(N-phenyl-3,4-dihydro-2H-1,3-benzoxazinyl)-(4,4′-hexafluoroisopropylidene)bisphthalimide (6FIBZ-a), were successfully synthesized. The structures of the benzoxazines were confirmed by Fourier transform infrared and proton nuclear magnetic resonance spectroscopies. The novel benzoxazines were easily dissolved in common organic solvents. The differential scanning calorimetric curve of 6FIBZ-apa showed only a single exothermic peak since oxazine ring-opening and acetylene addition polymerization occurred simultaneously in the same temperature range. The introduction of rigid and thermally stable imide moiety led to rigid molecular structure, thus resulting in an increase in the glass transition temperature and improvement in thermal stability. The thermal properties were further improved significantly by the incorporation of cross-linkable acetylene groups to increase the cross-linking density as evidenced by thermogravimetric analysis.