Ring Opening Metathesis Polymerization of Cyclic Allenes

The ring opening metathesis polymerization of cyclic allenes is described. Treating the monomers to a Grubbs-type catalyst afforded polymers that featured allenes integrated into their main chains, as confirmed through a range of spectroscopic, chromatographic, and chemical techniques. Acyclic, 1,3-disubstituted allenes were used as chain transfer agents in the aforementioned reactions. These additives not only provided the corresponding end-functionalized polymers but also enabled control over the molecular weights of the polymers produced. The polymers obtained from the ring opening metathesis polymerization reactions were transformed into silyl-containing derivatives using a hydrosilylation-based, post-polymerization modification. A polymerization mechanism was also deduced and proposed to proceed through a process that involved ruthenium vinylidene intermediates and selective chain transfer.