Synthesis and Characterization of a Lateral Phthalonitrile Functionalized Main-Chain Polybenzoxazine Precursor

A lateral phthalonitrile functionalized main-chain polybenzoxazine precursor has been successfully synthesized. The structure was characterized by proton nuclear magnetic resonance ( 1 H NMR) and Fourier transform infrared (FTIR). The formation of benzoxazine rings were confirmed by the characteristic resonances observed at about 4.55 (C-CH 2 -N) and 5.30 ppm (N-CH 2 -O) and the absorbance at 950 cm -1 of benzene attached with an oxazine ring. The curing behavior was monitored by differential scanning calorimetry (DSC) and in situ FTIR. The completion of polymerization was proved by the disappearance of the band located at 950 cm -1 in FTIR. Thermogravimetric analysis (TGA) was used to investigate the thermal stability, and the results indicated that the thermal stability of the cured polymer gained significant improvement than that without phthalonitrile functionalization.