Synthesis of Branched Polymers by Means of Living Anionic Polymerization. 13. Synthesis of Well-Defined Star-Branched Polymers via an Iterative Approach Using Living Anionic Polymers

Abstract

We have developed a new iterative methodology for the synthesis of both regular and asymmetric star-branched polymers. The methodology involves only two sets of reactions for the entire iterative synthetic sequence: a living linking reaction of either 1,1-bis[3‘-(1‘ ‘-phenylethenyl)phenyl]ethylene or 1,1-diphenylethylene (DPE) functionalized polymers with living anionic polymers and an in-situ reaction for introducing DPE moieties into the polymers. By repeating the two reactions in the iteration, a series of regular star-branched polystyrenes of A3, A6, A9, A12, and A15 types and asymmetric star-branched polymers of A3B3 and A3B3C3 types were successfully synthesized. There does not seem to be a steric limitation even in the fifth iteration. The A and B segments in these star-branched polymers were polystyrene and poly(4-methoxystyrene), respectively, and the C segment was poly(4-tert-butyldimethylsilyloxystyrene), poly(4-trimethylsilylstyrene), or polyisoprene. Their arm segments were precisely control...