Without chain crosslinking and degradation

polybutadiene (PB) was chlorinated with t-BuOCl to give chlorinated polybutadiene (Cl-PB) with labile halogen atoms on the backbone. Comb-shaped PB was prepared by coupling of Cl-PB with living PB in a mixed solvent of cyclohexane and tetrahydrofuran. Characterization by GPC and os-mometry showed that purified products were well-defined comb-shaped PB of low poly-dispersity

composed of a backbone chain carrying randomly distributed grafts. The ave-rage number of branches was able to be varied in a wide range to meet the needs of stru-cture-properties relationship study.