Macromolecules, Vol.50, No.2, 534-541, 2017
A Novel Approach toward Polyfulvene: Cationic Polymerization of Enediynes
Enediyne compounds have found limited applications in polymer science and material chemistry due to the poor regioselectivity and/or the step-growth nature in their radical polymerizations. However, the cationic cydization of enediynes exhibits a high regioselective 5-exo-dig mechanism, providing a new strategy for the synthesis of polyfulvene derivatives. The expected polymers were successfully produced by cationic polymerization of enediynes induced by CF3SO3H, and a well-defined conjugated structure was confirmed by NMR, IR, and UV-vis spectroscopy. GPC analysis shows a relatively narrow molecular weight distribution, and the molecular weight reaches up to 62.9 kDa. On the other hand, the structural features of the obtained polymers and the mechanism of the cationic polymerization were investigated through kinetic study and MALDI-TOP MS analysis, which revealed a second-order consumption of enediyne monomer and the polymerization being probably terminated through intramolecular abstraction of proton from the neighboring group.