A high performance polybenzoxazine via smart ortho

Monofunctional benzoxazine with ortho-norbornene functionality (oHPNI-a) has been synthesized via Mannich condensation. The benzoxazine monomer containing norbornene group can be polymerized by ring-opening metathesis polymerization (ROMP) to form a side-chain benzoxazine functionalized polynorbornene (poly(oHPNI-a)side) with number-average molecular weight 3840 and weight-average molecular weight 7290. The structures of synthesized monomer and side-chain functionalized linear polymer have been confirmed by 1H nuclear magnetic resonance spectroscopy and Fourier transform infrared (FTIR) spectroscopy. The further thermal curing polymerization mechanisms of poly(oHPNI-a)side are monitored by in situ FTIR and differential scanning calorimetry (DSC). Activation energy of polymerization for poly(oHPNI-a)side is also studied by DSC. The polybenzoxazine obtained by ROMP and further thermally activated ring-opening polymerization exhibits much higher thermal stability than the polybenzoxazine directly formed by traditional thermal curing