Synthesis of star-shaped poly(vinyl ethers) with many arms by living cationic polymerization

Star-shaped polymers of isobutyl vinyl ether (IBVE) with many arms (“crew cut” type) have been synthesized by living cationic polymerization using the HCl-IBVE adduct/ZnCl2 initiating system. A short living polymer (DPn ⪇ 30) of IBVE is allowed to react with a large amount of divinyl ether ([divinyl ether]0/[P*] = 10–15) to give soluble star polymers whose number of arms ranged from 40 to 120. The diameter of such “crew cut” star polymers reached ca. 20 nm.