Anionic Polymerization of 2-Phenyl[3]dendralene and 2-(4-Methoxyphenyl)[3]dendralene

Anionic polymerization of two phenyl-substituted trienes containing cross-conjugated carbon-carbon double bonds, 2-phenyl[3]dendralene (P3D) and 2-(4-methoxyphenyl)[3]dendralene (MP3D), was carried out in THF under a variety of different conditions. Poly(P3D) of controlled molecular weight with a narrow molecular weight distribution was obtained when the polymerization reaction was carried out at -78 degrees C for 30 min. Broadening of the molecular weight distribution to the higher-molecular-weight side was observed if the polymerization mixture was left to stand for 20 h at -78 degrees C, presumably because of the attack of the propagating chain-end carbanion at the conjugated diene structure in the polymer chain. Similar broadening occurred if the polymerization was performed at a higher temperature. However, under identical conditions, no such a broadening was observed in the polymerization of MP3D. Block copolymers of predictable molecular weights and compositions containing a poly(2-vinylpyridine) segment were obtained by the sequential addition of P3D and/or MP3D to potassium naphthalenide and then 2-vinylpyridine. Only the conjugate addition structure was found in the resulting polymers.