Norbornadiene ring-opening metathesis polymerization

During ring-opening metathesis polymerization (ROMP) of norbornadiene (NBD) with the Grubbs catalyst a free radical is also observed as a 1 2 1 triplet, which is also formed, but to a much weaker extent, with norbornene (NBE), cyclopentene and 1,7-octadiene. The identity of this triplet, and that of a transient doublet observed together with the triplet in the case of benzonorbornadiene, are discussed as well as the possible role of radicals in initiation of ROMP, crosslinking of ROMP products, and polymerization of a-methylstyrene. 

A type of ring opening addition polymerization using transition metal catalysts not unlike Ziegler-Natta catalysts is called metathesis polymerization." Metathesis polymers, first made in the 1960s, are called polyalkenamers. Polymers made from cyclooctadiene and norbornadiene have applications as specialty elastomers. The polymerization of norbornadiene can be summarized as follows ... 

---