Successive Synthesis of Regular and Asymmetric Star‐Branched Polymers by Iterative Methodology Based on Living Anionic Polymerization Using Functionalized 1,1‐Diphenylethylene Derivatives

In order to achieve the successive synthesis of star‐branched polymers, we have developed a new iterative methodology which involves only three sets of the reactions in each iterative process: (a) a coupling reaction of a living anionic polymer with 1,1‐bis(3‐chloromethylphenyl)ethylene to prepare a DPE‐chain‐functionalized polymer, (b) an addition reaction of sec ‐BuLi to the DPE‐chain‐functionalized polymer, followed by treatment with 1‐(4‐(4‐bromobutyl)phenyl)‐1‐phenylethylene to prepare a new DPE‐chain‐functionalized polymer whose DPE is separated by four methylene units from the main chain, and (c) a coupling reaction of 1,1‐bis(3‐chloromethylphenyl)ethylene with the polymer anion derived from the newly prepared DPE‐chain‐functionalized polymer and sec ‐BuLi. With this methodology, a series of well‐defined 4‐arm, 8‐arm, and 16‐arm regular star‐branched polystyrenes as well as 4‐arm A 2 B 2 , 8‐arm A 4 B 4 , and 16‐arm A 8 B 8 asymmetric star‐branched polymers comprising polystyrene and poly(α‐methylstyrene) segments have been successively synthesized.