Synthesis of well-defined star-branched polymers by using chain-end-functionalized polystyrenes with a definite number of 1,3-butadienyl groups and its derivatized functions

摘要

A series of new chain-end-functionalized polystyrenes with two, four, and eight 1,3-butadienyl groups (PS(Bd)(n), n = 2, 4, and 8) were synthesized by the reaction of chain-end-functionalized polystyrenes with the same numbers of benzyl bromide moieties with the 1,1-diphenylalkyl anion prepared from oligo(alpha-methylstyryl)lithium and 1-[4-(4-methylene-5-hexenyl)phenyl]-1-phenylethylene. These 1,3-butadiene-functionalized polymers reacted efficiently with polystyryllithium (PSLi) to afford well-defined 3-, 5-, and 9-arm star-branched polystyrenes. A successive synthesis from (PS(Bd)(4) to 5-arm followed by 9-arm star-branched polystyrenes was demonstrated by twice repeating the reaction sequence involving the reaction of PSLi with (PS(Bd)(4) and subsequent in-situ introduction of 1,3-butadienyl groups via the generated anions. The terminal 1,3-butadienyl groups were quantitatively converted into highly reactive anhydride and epoxy functions by the Diels-Alder and epoxidation reactions, respectively. The resulting anhydride- and epoxy-functionalized polymers were successfully used as new polymeric coupling agents to synthesize well-defined star-branched polystyrenes. [References: 33]