Living Anionic Polymerization of 4-(alpha-Alkylvinyl)styrene Derivatives

摘要

The anionic polymerization of four bis-functionalized styrene derivatives with alpha-alkylvinyl groups have been carried out in THF at -78deg C with the initiator prepared from oligo(alpha-methylstyryl)-lithium and potassium tert-butoxide.The four monomers herein used are 4-isopropenylstyrene(4),3-isopropenylstyrene(5),2-isopropenylstyrene(6),and 4-(alpha-isopropylvinyl)styrene(7).It was found that under such polymerization conditions,the vinyl groups of both 4 and 7 are selectively polymerized and the isopropenyl and alpha-isopropylvinyl groups remain completely intact to afford stable living anionic polymers.As expected,the resulting polymers possessed precisely controlled chain lengths and narrow molecular weight distributions.More importantly,they also possessed the pendant isopropenyl and alpha-isopropylvinyl group in each monomer unit possible for further modification.On the other hand,the anionic polymerization of either 5 or 6 proceeded more or less along with the unwanted side reactions leading to chain-branching,followed by cross-linking.The positional effect of isopropenyl group on the polymerization and the cause of possible side reactions were discussed.