Thermally curable polyoxanorbornene by ring opening metathesis polymerization

A novel norbornene monomer bearing a thermally curable benzoxazine group is synthesized and polymerized by ROMP using the Grubbs first-generation ruthenium catalyst. The M_w of the side-chain benzoxazine functionalized polyoxanorbornene can be up to 87 000 Da with unimodal molecular-weight distribution and narrow polydispersity between 1.18 and 1.65. Thermally activated ring-opening polymerization of benzoxazine moieties leads to the formation of highly cross-linked structures. The effects of molecular weight on the thermal ROP of polybenzoxazine precursors are examined. Synthesis and characterization of various polyoxanorbornenes with different molecular weights containing thermally curable benzoxazine units in the side chain via ring opening metathesis polymerization are reported. The thermally activated ROP of the polymeric precursors containing benzoxazine units are also investigated by DSC studies.