Aggregation, alkyllithium-initiated polymers

The formation of difunctional alkyllithium initiator from the adduct of 5-BuLi and PEB in nonpolar solvent enabled the synthesis of H-shaped polymers, regular combs, centipedes, and barbwires. ° Quirk and Tsai ° prepared a trifimc-tional alkyllithium initiator based on l,3,5- ri5(l-phenylethenyl) benzene and used it for the synthesis of three-arm star polymers in benzene. Three-arm star polymers exhibiting multimodal distributions were obtained due to the intermolecular aggregation of initiator rendering initiation incomplete or slow. The addition of a polar solvent such as THF (THF/Ii = 20) to the initiator solution in benzene produced three-arm star polymer with narrow MWD. ° ... 

N,N-diethylacrylamide (DEAAm) in polar and nonpolar solvents using alkyllithium initiators is complicated due to the presence of slow aggregation dynamics of the propagating amido enolate ion pairs similar to ester enolate ion pairs in alkyl (meth) acrylate polymerization. Attempts were made to use different initiators in combination with coordinating ligands to control the polymerization, and only minimum control on molecular weight, MWD, and the stereostructure of the polymers was obtained."""-"""... 

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