Living cationic ring-only polymerization

This mechanism represents a novel type of living polymerization in that the polymer "dies after each addition of a monomer tmit. The chain "lives and grows only as long as monomer is present to be activated by the catalyst. However, block copolymers derived from the addition of other monomers (e.g., isoprene) via this mechanism have not yet been rqwrted. Breaks in the fused ring structure may occur by cationic 1 2 or 1,4 initiation. 

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